well, Glassjaw is on the list because KWSN mentions them in nearly every post
but overall, i think the bands' appeal to internet forum frequenters is the same appeal that internet forums have -- slightly underground and slightly "intellectual". nearly any forum i've been on seems to love a fair amount of these bands, especially radiohead, a perfect circle, tool, and dream theater. why do i call these bands intellectual? well, i don't think they're very appealing at first listen, so listeners probably feel accomplished when they have acheived the acquired taste that is these bands.
my likes from the list are tool, opeth, non-cheese dream theater, glassjaw, and song-oriented radiohead (i.e. not their recent ambient sounds junk).