Okay, so this isn't mine, but I thought it may be useful to the community, so I posted it.
For those of you without a GMC (Game maker community) login (or just don't use it at all), I found this while browsing the game maker creations board. from my understanding, what it does is compress GM 6.1/7.0 files to about 1/2 their normal size (one of the screens on the site has something like 80% reduction rate), I'm not sure weather it compresses the exe's or the gm6/gmk files, look in the topic
http://forums.gamemaker.nl/index.php?showtopic=290637 yourself if you want to find out. also this
does not compress any other types of files.the only downside to this is that both the downloader and uploader need the program, which makes winzip a more popular choice.
the download link is in the topic, here
http://forums.gamemaker.nl/index.php?showtopic=290637