Personally, I like the Google Ads, but if you don't, you may want to try this URL from Google to search.
A search for "ipod" brings up about nine ads on the main Google Search. But the same search on www.google.com/search?output=googleabout displays no ads, but the same exact organic results.
How did they figure this out? It was not brain surgery. Go to any of the About Google pages, for example here and on the left side is a search box that says "Find on this site." Enter your search query there, let's say for ipod and up come results for ipod matches found at google.com.
Right, I know, that is not what you want. But by simply removing the "&sitesearch=www.google.com" parameter from the URL, you are opening up the search to all sites. Yes, ad free.
Forum discussion at DigitalPoint Forums.