I've been doing some research to find reliable sources for SEM (Search Engine Marketing) information. The conclusion I've come to is that forums and blogs are the best source because virtually all books on the subject become quickly outdated.

My two favorite sources of SEM information are the HighRankings Forum and the Cre8asite Forums. At both these sites you can post a question and receive an answer, usually within a few hours.

Tip: when you post your question, check the little box that says "Notify me of replies to this post". That way you will get an email notification when someone has answered your question (instead of having to check back to see).