hi
I'm looking for a slim and quite comfortable window manager for a unix/linux thin client?
xming one of 1st choices
isn't that a x-server software for windows?
a quick google came up with this.
The Comprehensive List of Window Managers for Unix
you might have already came across this list but nonetheless.
Hello, ccc:
"quite comfortable" is a very vague phrase. Elaborating on which features are necessary/optional would facilitate well-targeted suggestions.
Personally, I find dwm "quite comfortable". 
Regards,
Alister
For Linux, XFCE or LXDE are two good choices.