Another spinoff from my current library to optimize SWF/SWC files. Reducer is a tool that will make SWF and SWC files significantly smaller. There is currently a huge problem with filesizes. If you use the [Embed] tag with PNG images they are not compressed at all. For the Hobnox AudioTool we have been using the Flash IDE to export all graphics so that they are smaller which was a pain.
Now with Reducer you are safe to use [Embed] and then run the tool afterwards. It will compress all lossless images and make them lossy. But usually a PNG can be compressed at 100% JPEG quality and you will still safe a lot of data.
Note: You will not loose alpha transparency when using Reducer. The SWF file format allows us to use a special compression where a PNG gets split up into its color and alpha channels. The color channels are encoded using the traditional JPEG algorithm with adjustable quality while the alpha channel is handled seperately. Transparency is always stored in a lossless fashion which means even with a low JPEG quality you will not get any compression artifacts for the alpha channel.
Update: Reducer is now open source!