We just installed this interesting piece of software. It allows you to answer video chat requests just by pressing one key or by turning the lens cover on your iSight. Useful? Sure. Cheap? Sure. They offered Gizmodo readers 25% off until April 15 with the coupon code "GIZMODO." Check it out and see if it's useful yourself.
'Go!' keys. You can now use either the iSight camera (with an 'iTwist' of the lens), a key, or an external device (like a Wacom tablet), to answer and hang-up video and audio calls. There's a 'toggle' button too, so you can switch between the automatic fullscreen mode, and a small window (great for browsing whilst videoconferencing!).
Product Page [iTwistnGo]