UPX - the Ultimate Packer for eXecutables
This is a very valuable .exe that you can just drag-drop your .exe's on and it'll compact them (and make it a bit harder for newbies to decompile your program).
Ofcourse there are Unpackers for the people who really want to decompile your application, but you can at least enjoy the compression that UPX does. I used it on my last project file and it went from 208KB to 77KB.
I used the upx 1.24 windows console version.