Now that Google won't hold the 100 results, I use qrobe. Works great and I like the infinite scrolling. I hope they develop a toolbar. Another great FF add-on [which recently came out] which I'm psyched about is the Bargain Book Mole. Obviously for book buyers [like myself] who want to find the lowest prices online on the fly [i.e. you don' t have to go to another site].
Image search is awesome and the peek feature is incredible because you have full implementation of the right click (ie. you can save image,etc.) and I like how it doesn't have ads on the search pages either.
I was one of the beta testers for qrobe and was requested by the developer to provide my review here. I have been using qrobe for over 2 months, have really enjoyed using it and now use it exclusively. It does a very good job of combining results from the two best search engines (Google and Bing). I am a huge fan of its infinite scrolling feature and very clean interface. I can tell first hand that the developers put in a lot of effort to make sure that it works well across all major browsers, something that is personally very important to me. Give it a try you might get hooked too.