Quality Site-wide Text Links on the footer of everypage.
SlackwareHelp.org Text Link Ads.
I own http://www.slackwarehelp.org and I sell text links to support its growth. I will place these text links on the footer of every page for only $15 a month.
The forum is well over 1000 pages and has over 1000 articles. It is indexed very well by google and is #1 for many searches. I never paid anyone to post or anything like that. Just about all my visits come from revisits or google.