There's also Follow Friday -- basically, there's a meme of posting on Fridays reccing interesting people and comms to follow.

All public posts tagged with "follow friday" or "followfriday" get sucked up into the magic tag feed here:

http://www.dreamwidth.org/latest?feed=followfriday

So it's a good way for people to spread the word about comms they love.

Basically, I think there's not a shortage of places to pimp; it's just that many comms haven't yet quite reached the critical mass that encourages people to jump in.Though that's starting to change as the population of DW grows ...

I'm kind of evangelical about this, but the best way of boosting comm development is for people to jump in and start posting and commenting.