Ming-Sharp is an open-source (LGPL) library which allows you to create SWF ("Flash") format movies.
Ming supports almost all of Flash 4's features, including: shapes, gradients, bitmaps (pngs and jpegs), morphs ("shape tweens"), text, buttons, actions, sprites ("movie clips"), streaming mp3, and color transforms--the only thing that's missing is sound events.
Ming-Sharp is not an acronym.
Note that all values specifying length, distance, size, etc. are in "twips", twenty units per pixel.
That's pretty much arbitrary, though, since the player scales the movie to whatever pixel size is specified in the embed/object tag, or the entire frame if not embedded.