No Slackware takers yet? This is possibly my favorite distribution. It's a very "DIY" style of distro.
My machine is actually Slack 10.2 with some heavy modifications ... I keep up to date with the kernel, waiting on 2.6.24. In fact, many times it's not convenient for me to "upgrade" to Slackware 12 because of the customizations I've made.
Much of the emphasis in modern distributions has been on the gui, user-friendliness, and usability factors. Being a huge command-line fan, I feel right at home with Slackware.
People will ask me, (wanting to try a Linux distribution out) "which one is best?"
Well if I could answer that, I could also tell you what type of car you would like to buy and what you'd like to order from dinner from a restaurant.
My answer is always the same ... try a bunch out and see which suits you best!
To be fair, I also do like CentOS and Debian as well. They make fantastic servers. My "guinea-pig" machine at home will always be Slackware, though.
Any other Slack fans?