Just out of personal curiosity, how much disk space on the server does Stack Overflow take up? I'm guessing it's a lot, but I can't know for sure.
It was 12gigs compressed a few months ago, probably up to about 15gigs compressed (50 gigs uncompressed)
It is not a particularly huge database, most of the storage we have is taken up by history and indexes. Fitting most of our data in RAM is one of the reasons our performance is so awesome (that and Jeff's amazing wheel of blame).
When you look at perfmon: SQL server page life expectancy is massive, we barely go to disk.