"If you browse the menu bar on the left you will find a listing of a boatload of various derivatives tabulated by manufacturer to quickly compare their features."

Unfortunately this list is way out of date, you'll be better off looking directly at the manufacturers' web sites.

"Also, if you go to the Atmel site you can find documentation for their chips that includes a good description of the bootloader operation and the Intel Hex File format it requires."

I'm afraid that I can't agree with the use of the word 'good' in connection with their bootloader documentation. It has an MEPP of about 5...

MEPP: Mean Errors Per Page