If you're an early-adopter type, you may enjoy checking out Google's Experimental Search. There are a handful of add-ons that are still in the experimental stage that you can use to augment (assuming they work well) your Google searches.
My favorite one in the Keyword Suggestions add-on. It replicates one of my favorite Firefox features from the Google search page. Have you ever noticed how in Firefox, you can start to type a search term into the built-in Google search and it will start to auto-complete with popular Google search terms as you type? This add-on does that from the Google page, only a little better. It also includes how many search results each result will yield.
This is extremely useful when you want to see how other crafted their queries for the same thing you are looking for. It also helps when you are not quite sure how to spell one or more of your keywords. Example: it helped me get the spelling right when I was trying to research the Tunguska event.
Caveat: the Keyword Suggestion feature does not work with iGoogle yet. If you have an iGoogle page, you can only use it on subsequent searches - after you have performed your first search and are on the results page.
Anyway, I would recommend checking out Keyword Suggestions and the rest of the experimental features to see if any would work for you.