CuteRank is a free keyword rank checking tool. The free version will allow you to check the rankings of a single URL for several keywords over several different search engines; namely Google, Yahoo, Bing, Ask, and AOL. You can also base your search on the different regions these search engines serve, so you can get a better feel for how a site ranks in a particular location.
In order to look up the ranking of more than one URL, you need to upgrade to the Pro version.
This is a great tool for improving your Search Engine Optimization (SEO). Keeping an eye on your desired keyword rankings on a regular basis can help you keep your website among the top sites for that keyword, if not make it the top ranked website for that particular keyword or set of keywords.