I am as well. My agency has an account. They're tools don't do much that you can't do on your own for free, but they do put it all in one place which saves us enough time when doing market research that it justifies the cost.
If you haven't already, you should check out the labs stuff - http://www.seomoz.org/labs - which do things no other tools (that I'm aware of at least) can do :-)
And yeah, I know I'm biased, but I'm also very excited to have an article of mine posted to one of my favorite sites.
