A while ago I wrote this tool that uses the Yahoo API to find images then make banners that increase your CTR that go along side your conextual ads. I was not sure 100% if this was ok with Adsense or Yahoo Publisher Network’s TOS’s so I never published it and only used it with shoemoneyads
On last tuesdays radio show Barry talked a bit about Yahoo Publisher Network now allowing these sorts of images and also made a post about it here. Evidently YPN is giving the green light as long as the images are RELAVENT
If you would like to use the tool its located here. Simply put in a keyword, choose your 4 images then whola your banner is made. Please save images locally as they are deleted off the server nightly.
Always be sure to check with Yahoo or Google if you think you are violating the TOS at anytime.