A surprising number of GNU/Linux tools have animal names (rather than simply having animal mascots or logos).
First, obviously, there's :gnu, and also...
:dolphin-emu (two for one)
:firefox (apparently a red panda)
:pidgin (close enough)
Non-free, not on GNU/Linux or I don't use them:
dolphin (KDE file manager)
gecko (browser engine for firefox/icecat/iceweasel)
icecat / iceweasel
:munin (famous raven)
:ubuntu (release names)
:gencfsm (sounds like a sneeze)
See also | Meet the free software gang