From Apache to Nginx
I just moved all my sites from Apache to Nginx. It was well worth it.
I've just finished moving all of my website from the Apache web server to Nginx. There were more than a few hiccups along the way, mostly thanks to some annoying typos, but I managed it in the end.
It is totally in your interest to do this. Especially if you're on a limited VPS like I am (a 384MB slice from Slicehost). Nginx is extremely efficient memory-wise when compared to Apache (which seems to gradually use more and more memory. It's also snappier when compared to Apache in terms of speed of processing requests. I've noticed a large speed up of my database-heavy websites (like Gatekrash). I've managed to move the bottleneck from the webserver and the database to just the database now (my next target).
Anyway, thought I'd mention that.