Ask HN: Stats/Monitoring Sites you admire

I'm in the development phase for a web app that will track statistics for a website (traffic over time, etc. - no, its not a GA clone).

What sites do you admire in terms of layout, usability, usefulness, etc.? I particularly like clicky and mint interfaces, but I'd like to know of others. Don't feel limited to stats-heavy representations - if you've seen something you like, tell me!

Thanks to the HN community.