I have created a Google Custom Search Engine (CSE) that specifically searches the various search marketing and search engine optimization forums on the web. Currently, the Google CSE searches 14 SEM/SEO forums, and I have honestly been very surprised at how relevant the results have been. You can give the Google CSE a try over here or directly below. If you would like to recommend adding and forums to the Google CSE, feel free to comment here or in the original post.
Give it a try:
Postscript: Some people asked if they can add the CSE to their Google home page, you can by visiting here or by clicking here.