My server has a TV card in it so I can record TV using MythTV. It's connected to my Sky Digibox via quite a long bit of cable. The problem is that my Panasonic Digibox gives me a nice crisp RGB output, but my TV card has an S-Video input, so I'm reduced to using the composite output of the Digibox, connected to the composite input of the TV card... Composite video is really quite bad quality. :(
The solution, of course, is to go and spend huge amounts of money on an RGB -> S-Video converter. Well my wallet is feeling light enough as it is and I felt like a bit of an electronics project, so I had a look around for circuits on the web, but couldn't find any, so I had to design my own.