Nullifidian has recently created a new aggregator, Planet Humanism. Looks great, and I wish it the greatest success.
If you're curious, no, I don't think of it as competition to Planet Atheism. :) There's certainly room for both. As I've already told Nullifidian, the only potential problem I see is that the members of each aggregator will probably want to join the other, and will probably be eligible, so there's a risk that they will have something like 90% of blogs in common. But I hope that can be avoided (maybe there's some humanists out there who don't really consider themselves atheists), and it's great to have one more aggregator to read. :)
So... atheist or not, if you have a humanism-themed blog, go join PH. :)