I just thought I'd share the forums and sites I'm reading to keep in touch with the PPC and SEO community.

DigitalPoint Forums - http://forums.digitalpoint.com/
A reference. Forums about Search Engines, Marketing, Business, Design & Development... A big community with very interesting threads. More than 45,000 members!!

The V7 Network - http://www.v7n.com/forums/
Marketing and Web Development. A very busy SEO Forum. More than 17,000 members.

WebmasterWorld.com - http://www.webmasterworld.com/
Huge site, very known of webmasters. A lot of forums about search engines, PPC and webmasters news. But moderation is pretty strict and some sections are not free.

SEO Chat - http://www.seochat.com/
Lots of articles and nice SEO tools. (keywords density, meta tags analyzer, PageRank lookup...)

SEOMOZ.org - http://www.seomoz.org/
A nice site and blog about SEO.

Webmaster Talk - http://www.webmaster-talk.com/
Forum with a smaller community but growing. And interesting threads.

SEO Book - http://www.seobook.com/
Aaron Wall's blog about SEO.