I have a digital Rebel and read on photonet of a software hack that restores most of the custom functions and other features of the 10D to the Digital Rebel. Being the adventurous sort, I downloaded the hack and installed it. Voila! I have custom functions and other 10D features now on my Rebel. Most important restored features to me are:

Flash Exposure Compensation
ISO 3200
I can set the flash to emit an IR flash assist without firing. (Very useful for shooting in dark conditions with a 50 1.4.)

If you are adventurous too, here's where you can check it out:


If this ruins your camera, don't blame me! It worked for me, but I am NOT saying it will work for you! Installing this WILL VOID YOUR WARRANTY!! Beware!