Time Machine is the built-in backup tool in MacOS X 10.5. It takes a snapshot of files that have changed (by default it does this once an hour) and copies them to a sparse image on a USB, FireWire, or network volume (this typically requires an Apple Time Capsule drive or a MacOS X 10.5 machine sharing a drive - with a bit of hacking about it can be made to work with cheaper NAS configurations).
Jed has some nice things to say about Sun Web Server. In his nice things he also shows three tricks that are a pain to set up in other servers including use of the lookup() function to allow content owners to control expires headers for various content, URL rewriting, and conditional reverse-proxying to a back-end system.
See? SEE? More people should use this server. It's full of awesome.
Due to a really lame hack in PHP (when used as a FastCGI provider) to detect whether the HTTP front-end is Apache, PHP behaved really, really badly when used with non-Apache servers if the HTTP server provided both REQUEST_URI and SCRIPT_FILENAME. The end result was that PHP would throw "No input file specified" errors inappropriately.