Check out ReviewToolbar. It combats the web spam problem by showing ratings of web sites in the search results for Google, Yahoo, and MSN.

Another cool feature of ReviewToolbar is that it lets you "flag" previous sites that you thought were interesting so you can find them easily later. I frequently try to find sites I've found in the past by searching for them again in Google, Yahoo, or MSN. I have too much stuff in my Favorites list to be of use. This is a neat solution.