I installed Gentoo last week. Took roughly two times before I was able to do an install without looking at the documentation. I was quite disappointed in Gentoo given all the hype that surrounds it. It's certainly not ready for a production environment, but that really isn't the focus in this thread. Yes, you can minimize the packages on your system, but I consider the pain of the install, itself, not worth it.
If you want to have a minimal distribution, and you're willing to spend 4 hours - 1 day+ (depends on your hardware) installing it, go for it; it'd be worth your time in that case. It's a decent distribution to experiment with, however, it'd take you quite awhile to setup a server with all the packages you'll need. A Fedora "server" schema install would not install too many more packages (and you should also have some space left to boast) than all the dependencies Gentoo will build to install Apache, PHP, and MySQL. Sure, you'll have plenty of other stuff installed, but you never know when you might need it, nor will you have to wait to build the packages.