I spent a goodly amount of time trying to find the Lightning GTK Theme that comes packaged with Linux Mint 6 so that I could use it on Ubuntu. Although there is a version called Green Lightning available, it has been modified, and I wanted the exact same one Linux Mint has.
So, I finally loaded Linux Mint on my computer and copied the GTK theme over to Ubuntu. Since I had such a hard time finding it, I thought I'd post it here so others could share in the glory of this really cute GTK theme.
Keep in mind that I did not design this: I had no part in its creation and cannot take any credit for it. It was designed by the Linux Mint artwork team, and all accolades and donations should go to them.
This archive contains both the Lightning GTK theme and the Linux Mint icon set.