2012-01-10, 11:15 AM
Fedora 4/5 (home), CentOS5.5 (remote server), ubuntu (testbox), Debian (box I help maintain) amongst others. I've even run Apache under Windows several times (to demonstrate webserver configuration).
Apache is pretty similar across all of them, although I don't like the Debian-based method of "sites-available" and "sites-enabled" symlinks - just needs a bit more faffing about.