Even though they are two of the Internet’s largest advertising businesses, both Yahoo and Microsoft are without top execs to lead those units.

Worse, both are just entering a complex online ad sales and search partnership together, which will require a lot of management firepower.

Last week, BoomTown reported the departure of Yahoo’s head for the key North American market, Joanne Bradford, for a new job at social media start-up Demand Media. She starts there Monday.

It was a move that sent reverberations throughout the online ad market.

Less known, though, is that Microsoft (MSFT) has also been looking for almost a year for someone to head up its online ad sales force globally.

Yahoo (YHOO) is just starting its search to replace Bradford–with her boss, U.S. head Hilary Schneider, taking over on an interim basis.

In fact, even Yahoo CEO Carol Bartz is pitching in, giving Bradford’s staff a talking to earlier this week about the need to press on.

Both Yahoo execs said the company will be looking at both internal and external candidates.

Until then, said a Yahoo spokeswoman, in the boringest quote ever uttered: “Yahoo! has leadership bench strength and we continue to be committed in delivering wow experiences to both users and advertisers.”

Not to worry about obfuscation, as BoomTown has the scoop!

Internally, the key execs being eyeballed include 11-year Yahoo veteran Mitch Spolan, VP of North American sales, and Seth Dallaire, a former Microsoft exec whom Bradford brought to the company last fall as VP of mid-market sales, a newly-created role responsible for all mid-market sales efforts across search and display advertising.

Another former Microsoft exec, Erika Nardini, VP of brand packaging, is also mentioned a lot as a possibility and is well-liked by the sales force at Yahoo.

Still, many feel that with the exodus of such a high-profile exec as Bradford, Yahoo has to attract another big name to replace her.

But externally, the pickings are much slimmer, with only two key names popping up as top choices.

One is a former Yahoo, Jacki Kelley, a longtime online ad exec who is now North American president of Universal McCann, a unit of the Interpublic Group (IPG) agency. Besides Yahoo, Kelley has worked at Gannett’s (GCI) USA Today and Martha Stewart Living Omnimedia (MSO).

The second is Kathy Kayse, a well-regarded former AOL (AOL) ad exec, who now is in charge of digital ad sales at Discovery Communications (DISCA). Kayse also had a long career at Time Warner (TWX).

(Both are pictured here, Kelley at left and Kayse on the right.)

Microsoft is a dicier proposition, with exactly zero internal candidates considered qualified to lead the online ad sales effort, a job that would report directly into Corporate VP for Consumer & Online Darren Huston.

Microsoft has been searching for a long time now, with feelers all over the industry. A variety of names pops up, from new MySpace ad head Nada Stirratt to Bradford–also a former Microsoftie–herself.

In fact, the paucity of experienced execs to handle these complex jobs–which include the need to understand premium, network and search ad sales, as well as highly technical systems–is clear.

“Neither of these jobs are easy and, in many ways, a giant nightmare,” joked one online ad sales exec.

Microsoft is searching for a major executive to run its world-wide online sales, said several sources close to the situation, even as talks with Yahoo about a deal to partner in its search and display advertising businesses continue.

“They need to find a way to make money in display,” said one source close to the situation. “Or, I guess, find a way to not lose quite so much.”

The software giant has been trying to build its online business for many years now, spending a lot of money and not getting very much traction.

In its recent quarterly results, in fact, Microsoft’s online services got hit badly, with a 14 percent decline in revenue from a year ago to $721 million. Losses doubled to $575 million.

Sources said Microsoft (MSFT)–which has hired headhunting firm Spencer Stuart to conduct the search–is looking for more execs to turbocharge the situation, with one criterion being that the person hired is “another ambassador to Madison Avenue.”

Last fall, it did that by hiring Time Inc. ad exec Robin Domeniconi to take over as the new VP, U.S., Microsoft Advertising.

That’s why the new sales candidate the company is looking for might only be for someone to lead Microsoft’s international ad sales, since the exec in charge of that business left in December as part of a mass of changes in the wake of the hiring of digital head Qi Lu.

Those changes included the departure of that exec, Global VP of Sales Bill Shaughnessy, as well as its top online ad sales exec, Brian McAndrews, and the rejiggering of its online sales unit.

In that switch, Microsoft said in a press release: “The field sales organizations in the Online Services Group will move to Microsoft’s centralized Sales, Marketing and Services Group led by chief operating officer Kevin Turner. This group, called Consumer & Online, will be led by Corporate Vice President Darren Huston and will include the Global Advertising Sales and Services organization, led by vice president Bill Shaughnessy.”

The move to centralize, according to sources, has been controversial within the company, since it means all sales are being lumped into one megagroup.

That could all change dramatically again if there is any success in the talks Microsoft has been having with Yahoo (YHOO) about outsourcing its online display sales to the Internet giant. The pair have been discussing partnering over search and advertising.

While such a deal might not happen–Yahoo has been especially reticent to separate its search and display businesses–the two sides have been discussing several scenarios in a bid to compete with online giant Google (GOOG).

Among the latest ideas is one in which Yahoo would take over both search and display advertising sales and Microsoft would run the tech behind the scenes.

Such a deal would be a major shift for both companies in their business focus and would also tether them together.

In the wake of the changes at Microsoft’s online division, a senior advertising sales exec, Bill Shaughnessy (pictured here), is set to leave his post, the company confirmed.

The departure was first reported in Ad Age, which said Shaughnessy’s future plans were undetermined and, in fact, noted it was unclear why the longtime Microsoft (MSFT) staffer of 15 years was leaving.

BoomTown found the answer looking at the very bottom of the press release announcing the hiring of former Yahoo (YHOO) tech exec Qi Lu as head of its online services group:

“As part of today’s announcement, several teams will move to further align resources. The field sales organizations in the Online Services Group will move to Microsoft’s centralized Sales, Marketing and Services Group led by chief operating officer Kevin Turner. This group, called Consumer & Online, will be led by Corporate Vice President Darren Huston and will include the Global Advertising Sales and Services organization, led by vice president Bill Shaughnessy.”

The move to centralize, according to sources, has been controversial within the company, since that means all sales are being lumped into one mega-group.

Shaughnessy has worked on a range of MSN properties, as well as for the Windows group.

In his most recent job, he worked closely with Brian McAndrews, the top online ad sales exec at Microsoft, who announced he was leaving the company on the same day Lu was hired.

McAndrews had been a contender for the digital head job.

According to a Microsoft profile of him, Shaughnessy was global VP of sales, marketing and services, “responsible for the business leadership and management of its international business operations outside of the United States, including the Greater Asia region. His responsibilities include sales, marketing, business development, programming and regional and country management.”

Microsoft moved up its official announcement of former Yahoo (YHOO) tech star Qi Lu to be the head of its Online Services Group.

BoomTown reported on the selection earlier this morning.

As part of the changes, Microsoft digital ad head Brian McAndrews, who had also wanted the job, is leaving.

Here’s the full announcement from Microsoft (MSFT):

For Immediate Release
Dec. 4, 2008
Microsoft Appoints Dr. Qi Lu to Run Online Services Group
Yahoo! veteran to oversee Internet offerings for consumers, advertisers and publishers.

As part of today’s announcement, several teams will move to further align resources. The field sales organizations in the Online Services Group will move to Microsoft’s centralized Sales, Marketing and Services Group led by chief operating officer Kevin Turner. This group, called Consumer & Online, will be led by Corporate Vice President Darren Huston and will include the Global Advertising Sales and Services organization, led by vice president Bill Shaughnessy.