If you want to save yourself the headache just use nginx, it responds much better under load than apache. If you're using a dynamic backend such as PHP, RoR, django or something else you can really boost the number of page loads with reasonable caching strategies.
I just let Varnish do the hard work. I make sure my web app sets caching headers correctly, and then I just point Varnish at it. Instant 12,000 requests per second. I am sure if I spent time tuning the machine and setup, I could do even more. But my users make about 12,000 requests per decade :)
Varnish is great, and it's something I'd recommend to many people in many cases, but most people don't have their caching headers set granularly enough to not get caught off-guard by unexpectedly stale content at some point.
Gotta be careful, but if you know what to expect, Varnish is great.
Silly, how could they possibly find time to learn HTTP when they have to keep up with at least three blogs of mountebank victory bloggers in addition to learning the latest Drupal plugin?
