Every living thing, group, political party etc. is a "Special Interest Group." In fact some inanimate entities such as computer programs might be loosely regarded as Special Interest Groups because they allow people to do some things and not others.

I deliberately worded my note so that readers could see that those Web sites and bulletin boards would be ones that were themselves part of a Special Interest Group effort. But the agenda with them would be to try to move things forward instead of just saying that “This can’t be done” or “That is impossible.”