Some good advice below especially for any of you that still have "thin" affiliate sites or for datafeed affiliates that are still throwing up raw feed sites. (Are you? Tsk, tsk!) I hope everyone knows by now that
datafeeders need to be a little bit more creative these days.
Ymmm, looks nice & thick now! 
You can't just throw a feed site at Google and hope it will stick. A couple things you can do to make thin affiliate sites more rich, are to add
"prosumer" generated product reviews and ratings and other user generated content like blogs and forums. Tropical SEO has more ideas for you.
How to: Make a Thin Affiliate Site Thick "Problem: You have an affiliate site in the tried-and-true “ads as content” (product comparison directory) format, but it’s either not indexed, or not ranking.
Solution: Make your thin site thicker. Google respects thickness."
More...
BE SURE to read the 1st comment by Everett - great advice about adding regular non-affiliate links to authorative sites like wiki, howstuffworks, .gov and .edu sites at the bottom of your page and how that helped him.
whatcha think???
Thin Affiliate Site? Thicken it Up!
Linear Mode
