iChan.org is one of the lesser known chans out there for regular folk, but if you're something of a cock lover, you'll be happy to know that there's a small but obsessive community that posts here. There's currently just under 70,000 posts, although it updates on a slower schedule than most of the other gay porn image boards. There's also a bit of a focus on the sissy element of gay culture - you're free to submit your own bear submissions, but that's not the focus here.
It's not as big as the other places, but it's still a welcome alternative that you might want to populate with your own material. iChan.org does go down from time to time though, so be prepared to have bad days at work followed by your favorite image chan not being available. It sucks, but hey, that's the price you have to pay when it comes to getting free gay porn, right?