the best seo tool according to me is www.seodigger.com, it will show u all the keywords with its count and positions and thats for Google and MSN. Its really nice tool...!
I recommend you SEOAnalytic.com . It has many useful seo tools and they are all free to use with no limitation at all.
Here's one more vote for the tools at seobook.com. I like the rank checker especially - it's free, it doesn't have limits, and it keeps a history!
I am developing a fairly new webmaster tool site. Its not much now but I am working on a custom keyword tool that will most likely be released in Sept 2008 Web Tools SEO Give it a look. -