O cant believe i forgot to bring this up before, probably one of the only useful "mods" you can do. not really a mod, but its definitely modifying something. a friend showed me that if you set your primary and secondary DNS settings to a certain number, it will deny all updates to the firmware, and games. useful if you find a glitch (if ur into that kind of thing) because you can keep it from being patched over. also for if you jailbreak a ps3 using Custom Firmware, whenever the next update comes out you don't have to re-jailbreak. you can still play online even with outdated FW.
i have it written down some where, ill post. Disclaimer: i will not be held responsible for you using this as im pretty sure sony will not like you very much. lol