Check out this thread on xda about using UPX compression on oems. It compresses the .exe which makes it smaller and in most cases loads into memory and opens faster. It will also let you add more pkgs into rom and can be used with LZX compression. For example it compresses the opera exe from 6.5mb to like 2.5mb saving 4 mbs for other pkgs.
http://forum.xda-developers.com/showthread.php?t=481880
Ive been using it for a few weeks and it works well. Compress the .exe in oem pkgs before cooking for best effect. There are upx compression apps to compress it after its already made into rom but doing it that way will not reduce your rom size.