An oldie but a goodie. In episode 16 of Steel Angel Kurumi, Karinka has a dream that she becomes stronger than her sister by kissing the main character and aging up (She starts out as a chibi form.)
Her legs and arms don't have any real animation and just get longer, but her breasts and butt both grow (making some very sexy noises while it happens mind you) and both are very nicely animated
Happens at 3:10
http://sgvideos.net/video/bLjAG6l/st...mi-dub-ep-016/