Just a listing the Software-Related mascots I think are cool.
Wilber, The GIMP Mascot
Wilber looks pretty fitting. It gives a nice touch to GIMP. Not only does it represent the GNU Image Manipulation Program(GIMP), it also represents the Open-source world.
Herley, The Darwin Mascot
Looks pretty cool, though a weird mixture of the devil and the loony tunes.
The BSD Daemon
Another good-looking devil.
The GNU Wildebeest
Looks good. I think it has a sense of humour. I like it a lot, especially as it represents GNU, which is one of the greatest strengths of the open-source world.
Duke, the Java Mascot
One of my favourites. It looks cool and wacky. It also gets regularly updated by the folks at Oracle.