Great website - very simple + nice interface which is huge for a website like this. I especially like the contributor's functionality where you can send out the mockups for feedback. In the past, where I've been on teams that had to send out jpgs of the designs plus maybe a surveymonkey survey, your website puts it all together for the necessary feedback people need.<p>Even better is the create a "clickable" website part. I didn't really see that until I made an account (though I just looked back and saw it on the homepage). I think it's really important to have this functionality. I used to copy jpgs into powerpoint to try to simulate this somewhat.<p>I agree with the comments about pricing above perhaps being a bit low. When I saw this "Compare" page: <a href="http://mocksup.com/compare" rel="nofollow">http://mocksup.com/compare</a>, it's obvious that Mocksup has a lot more features, but is lot cheaper than the other services (none of which I had heard of). I guess on the one hand low pricing is good, but it's almost too low because it made me think, why would these others be able to price so much higher? That almost made me want to go to the other sites and compare, when I probably would have just signed up with yours right away (I didn't though as I was really impressed with Mocksup). Great stuff over all. I'm a new user.