I've been testing the upcoming 4.2 release of the Nessus vulnerability scanner. The new Flash-based web interface is awesome. It runs smoother than the standalone client and has a great feature under the Reports section for comparing two scan results, which is great when you have a baseline to compare current results against. The first link has two video, and the second shows the compare functionality. I'll be posting additional notes and screenshots as I spend more time with the beta.
The Academy Pro has some excellent videos showing off the new features of Nessus 4.2.
GFI videos. They're currently giving away free T-shirts to bloggers. :-)