WATMM is certainly interesting. As such, what other communities are you involved with that you find unique or special in some way? I think it's important, with such polarization online these days, that creative types have a place to feel included and heard. It's leveraging technology for the better, imho.
Here are a few that some of you might also find worthwhile:
VI Control - geared toward the cinematic and TV scoring crowd. Worthwhile discussions on a variety of topics.
Lines - this started as a space for monome users, but has blossomed into a very thriving community. All range of electronic music discussion takes place and has a nice mix of ITB and hardware folks.
KVR - an older forum that covers a breadth of synth and sampler topics. Tends to be more of a snake pit, but there is still useful information that can be gleaned in the sub-forums.
Mod Wiggler - as the name implies, geared toward modular users, but has a few subs outside of that niche.