CrowdEye, the Twitter search startup led by former Microsoft manager Ken Moss, today is launching a new service that ranks the influence of Twitter users on a score of one to 100.

You can think of the CrowdEye score kind of like a Google PageRank, which assigns a numerical ranking to websites, showing which are most influential. In CrowdEye, top Twitters receive a score of 100, though no one has yet achieved that milestone. Nobodies get a score of one -- since Moss said "zero didn't quite seem right."

At the top of the charts right now is actor Ashton Kutcher (score of 96), followed by Ellen DeGeneres and Britney Spears (CrowdEye scores of 95). (My CrowdEye rank is only 42, so guess I can't compete with the celebs).

Other services also attempt to rank Twitter users, including Twitterholic and Twitterank.

At this point the service is only available on CrowdEye, though Moss said he'd love to have the rankings or its "suggested follows" service integrated directly into Twitter. But that's not in the cards in the short term.

"Right now we're just focusing on helping our customers get the most value out of the data in Twitter, and we see a lot of room for innovation ahead," said Moss, who spent 20 years at Microsoft including a recent role as general manager of Live Search.

Of course, as we've pointed out in the past, it can be extremely challenging for a startup to attempt to build a service on the back of another platform. (The most recent example is the low valuation placed on Seattle music service iLike).

In fact, former Mpire CEO and current RealNetworks exec Matt Hulett touched on the difficulties in building on another's platform in a post last month. And he pointed specifically to the new Twitter-based startups, warning them that the microblogging phenom could one day simply wipe them out.

"Entrepreneurs listen," Hulett wrote. "Own your own dirt. Be careful when you build on someone’s platform."

Moss certainly is aware of those challenges, but he's pushing forward anyway.

"We do not intend for CrowdEye to become a full microblogging platform," he said. "We believe that continued growth in Twitter usage will driver further value not only into Twitter, but into the entire ecosystem Twitter is creating -- including apps like CrowdEye.