14. Natty Narwhal (11.04)
The narwhal is a medium-sized whale that lives year-round in the Arctic. Weighing up to 3500 pounds, the males of the species are distinguished by a long, straight tusk.
As for Natty Narwhal, well, readers of these pages are probably familiar with it already, if nothing else then by word of mouth. This version, after all, is the one where Unity became the default interface in the desktop version of the software--to the delight of some and the chagrin of others.