Hey Zack,
Firstly let me say that I love the idea. I can see it being very valuable. I am working on an idea myself, and I can definitely see us using this service once we are ready - who knows when that will be. I am sure you know how that process goes.
Secondly, I must also commend you for charging from the get-go. The price point seems good, what I was looking for though was a 'pricing page' that tells me what I am getting for my $20/mo and other plan options. I would also like to see other options, say only 3 or 5 keywords with a more limited account for $10/mo. Couple that with a 15-day free trial (7-days I think is too short) and you reduce the risk significantly for the customer. Imagine I am able to add a few new clients in the first 15 days...that's significant value-add.
Thirdly, I am sure you guys have thought about this already but I can see other things like 'recommended keywords' based on 'successful keywords' that the user has chosen. Those can be derived by finding a 'high correlation' between those keywords and other successful keywords chosen by other users for example.
Fourth, I am not too perturbed by your site design. You can always do a re-design, I would focus more on adding features to the $20 account, because it seems a little feature light at the moment.
That's all I can think of right now. Good job. I would love if when I am ready to use it (maybe a few months from now) I could get the 7-day free trial...or who knows maybe by then you have implemented a 15-day free trial on all accounts :)
One last thing...did you find the cofounder you were looking for and did you go it alone on this project? Would love a similar post to your hiphopgoblin post :)