I remember having spotted a link to a huge page with different equations to non linear interpolation curves, for example if you want to stop a car smoothly, etc.
Those can sometime be useful to emulate some real-world acceleration/velocity behaviors without the help of a physics engine, which can really simplify the code.
Any idea where this page is ? I can't manage to give google the right keywords...
EDIT: I just searched on my previous laptop bookmarks, and I found it: http://sol.gfxile.net/interpolation/