One of the more interesting aspects of Second Life is that you can customize your avatar into any shape, form, or contortion that you can imagine and then some. The sheer variety you can spot if you keep your eyes open is amazing.
The best places to check out all this out is at an infohub. Infohubs are unusual creatures, because I've never met one that gave out any useful info. They either spam links at you or have 'freebies' (if by free you mean you have to pay a small amount in) available. They're really only used nowadays as a holding pen of sorts for newbies, or a general haunt for regulars. It would be better perhaps if the infohubs were somewhat pretty, but most are not. Most are just a square block of concrete with benches lining the rim, and a teleport spot in the center.
One infohub I happen to prefer is the Bear Dream Lodge Infohub, in the Bear Sim. It's one of the nicer infohubs, and it has a small lodge of sorts with an camp area behind that. And that's where I captured some of these unique avatars. So, without further ado, and in no particular order:
The one above was not taken at Bear infohub, but hey, where else are you going to see a giant robot tango with a jelly?
The one above is another non-Infohub pic.