I routinely use Craigslist.com to post free classified ads targeted at products I find on clickbank. If you have experience in article marketing this method should be quite easy as I apply basic article marketing techniques to know what keywords I place my ads under in craigslist.

Why Do I Use Craigslist?
I have placed classified ads on numerous other free classified ad sites and have found that everytime my craigslist ads get higher placement in google under the keyword I am targeting. Ya sure they still get clicks on the other classified sites but what I have found is that craigslist.com will always get you "TEMPORARY" top placement in google for a keyword that you are targeting.

My Strategy For Finding Products And Keywords That will Rank High
As I said basic article marketing principals apply but this is what I have found that works best.
1) Use your basic google keyword tool and look for niche keywords with approx 6,000 searches per month. This will equal on a average day a potential 200 clicks on your ad that you have a temporary top placement for.
2) When you have found a keyword that you would like to target that is supported by a product that you would like to promote the next step would be to pop that keyword into your google search bar. Example " toe nail fungus removal" has 162,000 results W/o quotes. and only 85 with quotes. I also look at the information included in the results and I look for things like
-Are there authority sites listed on first page like .edu or .gov or pages with high page rank
- Or are there sites with low page rank and hub pages and article sites listed.
If there are authority sites listed I usually will bypass that keyword and dig a little deeper. If I notice that there are ezinearticles other various hubpages with low page rank I will usually place a ad. If you notice for this particular example there are ezinearticles listed on the first page.

Don't be surprised if you see a craigslist ad for this keyword on the first page VERY SOON.