The natural light in our house is absolutely awful and I normally have to use flash when taking photos of my cards. I find this really washes the colours out and makes them look quite flat. Of course there's also the issue of glare from the flash, particulary with glitter, mirri card, etc.
Recently I brought a photo studio light tent kit from eBay for about £34, which came complete with light tent, tripod, two lights and four different coloured backgrounds. It's absolutley brilliant and is going to mean i'll be able to take much better quality photos (i'm also loving the black background as it looks really professional).
I used it to photograph my last card - what do you think?