Git

Here's a pretty good article about git:
Understanding Git Conceptually

Virtualization

When I got my laptop 3 years ago, it came with Windows XP on it.
Rather than blow away an actual licensed copy of Windows, I
configured it to dual boot Windows and Ubuntu.

Until recently this worked OK, but lately something in Windows kept
blowing away the GRUB boot loader.  Every single time I booted
Windows, I'd have to reinstall GRUB afterwards.

Finally I had enough of this... over the weekend I used VMware
vCenter Converter to virtualize my Windows partition.  Now I can
run it from Linux with VMware Player. 

There were a few little hitches. For some reason bridged networking
didn't work, but NAT networking did work. It made me re-'activate'
Windows with the original key.

Both Converter and Player are free downloads.