There's a discussion on Thumped about the merits of 'visuals' at gigs/shows. Personally speaking, I'm all in favour of some sort of visual show to accompany the music, especially when the music of the particularly chin-stroking variety. Although I can see where many people's complaints are coming from: it gets very tiring seeing the same handful of movies being chopped up to make a visual backdrop.
So that's why I think something like EffecTV is such a good idea. Armed with a computer running Linux and a webcam, you can create some pretty interesting visuals in real-time, for a tiny, tiny budget. Installation (on Ubuntu, at least) was a snap. And it goes some way to providing a middle-ground for the people who don't want to spend the night looking at a DJ nodding his head and people who don't want to see the same old stock footage soaked in irony.
Here's a shot of me playing with it earlier - not mind-blowing, but bear in mind that this was being displayed on my desktop in real time.
Side-note: Jesus, I really need to trim my beard.