Some time ago I've found this thread:
http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=2102851

It was great idea, but I did not like that edges of mattress are not dynamic. Figure cannot sit on bed, can only lay in the middle.

I've tried to solve problem. Here you can see results:
http://www.youtube.com/watch?v=TxxOex2p15E
http://www.youtube.com/watch?v=fz68QGctPds

Animations are very short but they should show effects not story ;)
If you find it useful I can explain process.