GP-100 Tips and Tricks.
Check out the Harmony central effects database for the gp-100 to find reviews that owners have written. It's a good way to find out what practical experience people have had with the GP-100. Harmony Central, in general is a great web resource for musicians.
The Roland web site has some good info about all Roland products.
Many people want to know the difference between the GP-100 and the related GX-700 processor. Here is a comparison between the two.
If instead of a GP-100 you have the GX-700, here's a GX-700 Web site.
The support of control via MIDI is excellent on the GP-100. If you're interested in the details of the MIDI specification for the GP-100, here's the full spec.
The Roland GP-100 press release contains some info about the GP-100, but is really only of historical interest.