A few months ago I purchased a Logitech QuickCam Orbit AF and while the form factor is a bit odd, the mechanics, the software (RightLight™ 2, specifically) and especially the optics are amazing. The Zeiss lens combined with the RightLight&tm;2 software kicks serious ass and puts out the best video of any webcam I've ever seen. It's just phenomenal and I think most of the great picture comes from the great glass in this thing.
Where the Orbit really shines are in odd lighting scenarios, something quite common to desktop broadcasting. The combination of the amazing lens and the RightLight™2 (pdf) software that does spot metering, dynamic frame rate/exposure adjustments, removes noise by refreshing static content less frequently, and other tricks to dramatically improve the quality of the video, automatically, make this camera and software bundle a really compelling package.
The Orbit has three minor downsides. The auto-focus is a tad slow, the form factor is pretty odd and not very versatile, and when sitting atop its extension pole, it can get a bit shaky. I can live with the auto-focus slowness (we are talking about a $100 camera here :-) but the form factor and the shakyness when extended make getting a direct and level face shot difficult. Other than that, I couldn't be happier -- especially with the video quality.
Looking for a form factor that would sit atop my LCD screen (the Orbit sits on the desk and comes with a 12" extension that doesn't lift it high enough for a straight-on face shot,) and having had such a great experience with the Orbit, I opted to get the Logitech QuickCam UltraVision SE, a slightly lower resolution camera with a fixed-focus glass (not Zeiss) lens. The camera is the right form factor for putting atop my screen and giving a nearly straight on face shot.
Unfortunately, the optics on this model are just piss poor compared to the Orbit. Even the quite amazing RightLight™2 software wasn't able to make the picture quality anywhere close to that of the Orbit. And I'm not so much concerned about the missing pixels. I was fully aware of that when I got the camera. It's not the resolution, but the quality of the picture. It was so poor that I had to check if maybe there was some piece of protective plastic film covering the glass.
Looking back over the Logitech site and a few webcam reviews, I think I probably should have gotten the QuickCam Pro 9000 which comes with Zeiss glass and a 2MP sensor - possibly even the exact same lens, AF, and sensor setup as the Orbit. I'm going to see about ordering that one and will let you know how it goes.
If you've got suggestions for a ~$100 webcam that's going to impress me as much as the QuickCam Orbit, please let me know in the comments