Great discussion! A few comments:
There are people that call themselves experts at "link building" and then pay people in India, China, Philipines, etc. to go to blogs, forums, etc. and post comments with links to other sites. These links are usually in their signatures and/or posts and often have nothing to do with the thread or even the subject of the website. The goals are to:
1) Build "link popularity" so the search engines will follow the links and hopefully build up their sites search engine rankings (SE's are usually too smart to be fooled by these techniques)
2) Get people to click the links
The best things to do if you see spam are to 1) NOT CLICK THIR LINKS (2) Click the report button on their posts!
Regarding moderators: We appreciate all the members that help us keep things running smoothly. Fortunately we've not really needed much moderation on TEG, so we haven't even thought about looking for new moderators.
There are great ways to help with the forum without actually being a moderator:
1) Set a good example
2) Don't participate in any flaming / trolling
3) Encourage others to follow the rules
4) Report problems so we can review them
5) Have fun!!!