Yesterday, I was a judge on a three-person panel at the Under the Radar: The Business of Web Apps conference, held at Microsoft’s (MSFT) Mountain View, Calif., campus in Silicon Valley.

The event, sponsored by Dealmaker Media, was a very good version of many such conferences held often around the region, where start-ups come to show themselves off in what amounts to a geek version of “American Idol.” There were just over 30 companies there yesterday.

In other words, entrepreneurs come to make a PowerPoint pitch before the panel and the audience and then we get to ask questions and make comments, a la Simon Cowell.

(I tried to channel Paula Abdul, but 10:45 a.m. is much too early to start drinking–um, it’s just Diet Coke!–for me!)

The companies I judged–with Stephen Stribley of Microsoft Office-Live and Hummer Winblad Venture Partners’ Prashant Shah–were in a category called “Manage Up.”

That meant they were all essentially in the enterprise-software-as-a-service arena that has gotten–and will get–increasingly hot.

The group I judged included: Act-On Software (an on-demand Internet communication and collaboration service), Magento (an open-source e-commerce), Mumboe (an online document-management service), and NetBooks (a Web-based business-management system).

All were interesting and promising, although all had issues, from security to marketing challenges to, of course, bigger competitors.

I did a video of snippets of the presentations of all four in a row, starting with Act-On, as well as a little interview with one of my favorite VCs–but only because he is funny–Mitch Kertzman of Hummer Winblad. He was there to support several of his investments, including SlideRocket (an Internet presentation application).

Here’s the video: