I’ve used a number of keyword trackers, which indicate your ranking in SERPs(Search Engine Results Page). However, the service that offers the fastest results and unlimited keywords is Digital Points own free tool.
The Keyword Ranking Monitor will record your results on a daily basis across Yahoo, Google, and MSN. In addition to providing your rank it is also able to track your results in a graph and did I mention it was FREE.
If your considering doing any SEO, then this tool is a must have. It definatley helps qualify your efforts, instead of just guessing at traffic. Be sure to check out what else they have over there as well, more goodies than you can shake a stick at. One word of warning, use their Free Advertising at your own risk.