What we've done: Trent's rented a couple more
small (512MB) Linodes to
experiment with, and put Squid on them. And we've abandoned page
counts, to slight angst from the users. So far, just running what we
can through a Squid has done *wonders* for the main server. w00t! Now
to see how our next burst of popularity goes ...
If you're already using FastCGI, go ahead and drop apache in favor of
nginx/lighthttpd or something similar. Unless there's some reason you
absolutely need to stay with apache, less resource intensive
alternatives are out there.