OS X + Linux: perfect combo! Also: request for advice on SuSE Linux dedicated server providers
I am finding the combination of my Mac OS X desktop (and iBook :-) running an X11 display with SuSE Linux for servers on my own network is just about perfect: I prefer SuSE's Yast administration tools and keeping Yast open as required for each server with the display set to my Mac is just about perfect.
For customer installations, I usually use rented servers at 1and1.com and serverbeach.com but they only provide Redhat Linux based servers.
Sometimes, I like to do development under Linux in addition to OS X (for a few different reasons) and here again, OS X's X11 support makes it pain-free to develop on Linux: for example: great looking Mac fonts, not need to use the Linux server's display (actually, I usually run Linux boxes headless around here :-), great for offloading long builds, etc. from my desktop OS X box, etc., etc.