Is there an official list of the largest sites running RoR?

Our site is growing fast & the last few weeks, we've been running into a few scalability issues. For reference, this month we're generating more than 600,000 unique visitors, and on a given day, we get an average of 350K unique requests between robots, users, pageviews, stylesheets, etc.

The site is all running on one webserver, which runs apache, mongrel, and posgressql. I know we're not the "biggest" site out there running RoR, but it seems like we have to be in the top 10-20. Is there an official list of the largest sites running RoR? The reason I'd like to know is for example, the guys at 43things post a bunch of technical info, same with the revolution on rails blogs, both of which are huge contributors to the community & my own understanding (I'm the marketing / product guy, not the technical wizard).

If you know of any good lists like this, or can send them to me, I'd really appreciate it. Thanks!

There's not much out there, but is probably the biggest in terms of hard usage (11,000 requests per second). is pretty big too, and they have been quite clever with some monster caching server (RAM in the Terabyte range for their cache server, and about 99% cache hits).