A Post by Ann Smarty over @ Search Engine Journal -
Online SEO Tools - the Ultimate Collection: "All tools listed below fall under the following criteria:
they are all useful for SEOs; they are all web-based (no desk-top ones or FireFox extensions so far); they are all free."
DISCLAIMER: Ann Smarty is an Search Engine Journalist, her opinions may not be the same as my own. However, it looks like she put a good amount of time into this post and while some of the tools mentioned, may or may not be "google-friendly", (as with any tool that automatically uses bulk queries on a search engine), please use with caution. She does have a good grip on SEO, so it's definately worth a look.