Have you heard of Googlefight? It runs a search on two concurrent search terms or phrases in Google, and returns the number of results. The search is accompanied by a short stick-figure animation. (The site is not affiliated with or sponsored by Google.)
Googlefight promotes itself as a game-type site, but it is very useful to get comparative statistics on web content and word usage. For instance, writers could use it to check on the relative popularity of variant versions of idiomatic phrases. For instance, according to Googlefight, "pesky library" is much more common than "pescosolido library", and the misspelling "definately", compared to "definitely", comes up about 7 % of the time on the web.
P.S. Don't forget - the common book author Brittany Perham visits the library tomorrow, April 19th, at lunchtime!