VMware workstation 5.5.1 - improved kernel module compilation!
The best feature with 5.5.1 compared to version I ran previously is that it manages to compile its kernel modules for the stock Debian 2.6.8-2 kernel. Earlier, I had to run 2.6.8-1 for this to work, with known security holes :-(.
I generally try to use Open Source software, but VMware is one of the exceptions. Especially since my employer pays the license.. :-)