There are some software programs out there that let you create different animations and poses for you 3D models. Second Life only allows you to upload poses and animations for the BVH format. This motion capture format was originally created by Biovision and lets you work with bones and joints within your models.
The most popular software that I keep hearing about is Poser from e frontier. This program goes for about two hundred and fifty US dollars. An open-source program that also supports the BVH format that is available is called Blender. I tried out Blender once and it was very confusing to use. On top of that, Blender is not focused specifically on posing your models. It’s an entire 3D modeling suite.
I recently discovered a little program called Avimator. It is a simple tool specifically for animating avatars in Second Life. On top of that, it is free and recently released as open source. I was able to quickly position the character and animate it in the program the way I wanted it to move. I uploaded the BVH file and was able to see it in action.
I have problems opening my saved files. I can’t position the body so that the feet don’t move when doing a hula hoop animation. The program is still faily new. Really, really new. I wouldn’t be surprised to see this program get a lot of functionality added to it over the course of time. So far the creator has been pretty helpful. The author is accepting donations as Lindens in the game.