[ericabiz]

We have one as well (built from the ground up--my co-founder and I started building it in October 2010!)

http://whooshtraffic.com/rank-tracker/

Our rank tracker also has a competition analysis tool attached--so you can get data like # of backlinks, etc. for the top 10 Google results for any given keyword.

[Ixiaus]

Co-founder weighing in here, for you HN geeks we use Erlang, RabbitMQ, and Riak for our rank tracker software.

[robertp]

Interesting, I will give this a try tomorrow when I have company CC #