spritesheetlib - pygame lib to load spritesheets
Spritesheetlib loads sprites from a spritesheet using a sprite sheet definition file in json format. There is also a generator for sprite sheed definition files for spritesheets that don't have a sprite definition file. The sprite sheet definition file is in a simple format so loaders for other lib than pygame should be easy to write.Here is the link to the project page on pygame.org.
Features: support for polygon shaped sprites, sprite sheets with non grid arrangment, properties and grouping by property and a few more.