Ad placement on web sites is an slippery slope.  We have tried to keep the ads really unobtrusive on the InstantSpot member sites, but still try to figure out a way to (hopefully) make it worth our time.  

We originally were going to go for the one text block in the right column, but we just were not seeing the performance we need (dismal click through ratios).  Thanks to the comments from one of our members on one of my related blog posts , we started running a small link block below the content.

Believe it or not, we saw an immediate increase in clicks.  Now, it still isn't time to pack up and leave the day job, but it does seem a lot more plausible that with a ton of users it could generate some ad revenue. 

Moral of the story:

Pay attention to your ad placement.  Check out Google's heat map for some ideas.

(You will notice, the "hottest" section on the map is the one that the InstantSpot user gets to claim for him/her self.)