Modding a PS3 now is almost worthless. Although there are rumors of a new dongle coming out, take them with a grain of salt. For a while, the PS3 scene was on fire when the CFW (custom firmware) first came out. Problem is, the CFW requires a certain official firmware to be able to run, and all new games require a firmware upgrade to play. However, there are some games that come with "fixes" that allow you to play them with older firmware.
As for the 360, you have a couple of options. You can either get a JTAG. It is used to play games off of an external hard drive. Second option is to get your 360 flashed. This allows you to play burnt games, but Microsoft is always coming up with new security measures, almost on a tri-monthly basis now, that requires you to constantly update your flash. The newest security measure, XGD3, even makes you buy a new DVD burner, which you then have to flash with custom firmware to be able to burn "proper" games.
The third method of playing backups on a 360 is to get the new ODE's, also known as Optical Disc Emulators. Attach a external hard drive to one end, and the other end hooks up to your console, and your good to go. Although there a quite a few versions out, all of require different methods of installation.
I can go into a LOT more detail on all three methods of modding your 360, but for now, I think that should be enough

. If you have any questions, feel free to ask.
Also, I don't have a PS3 myself, so my information about it may be incorrect. Other than the PS3 though, I have modded/flashed/hacked almost every other system out there, so the info on the 360 should be correct.