Here is a useful accessory that I picked up the other day when I was wandering through a local camera shop while waiting for my wife in the mall.
The "Lumiquest Soft Screen" is a simple vinyl and plastic diffuser that will adapt to most popup flashes and will fit in a shirt pocket without much more fuss than an index card. At around $13.00 it is in everybody's budget and can make the quality of light from your, on camera, popup flash much more pleasing. Sometimes an accessory like this is more trouble than it's worth but I found this one, to attach easily and convenient to carry. I purchased this to put on my Canon Rebel XT.