(This is a cut-and-paste of something I sent in response to a similar question about FreeBSD last month.)
I've been a customer of Panix (panix.com) for years and they're terrific. Inexpensive, flexible, responsive support, VERY high clue level, and proactive about patches/fixes. (There have been multiple instances in which they've fixed something before I knew it was a problem. They're fast, but deliberate: I don't think I've observed any instances where they had to back out a change.) They're also good about supporting pretty much whatever distribution you ask for: if there's customer demand/requests for it, they'll make it happen. ---rsk
