Hacking your Slim PlayStation 2 allows you to do many things that you normally could not do with the console. While hacking your PS2 can be both fun and rewarding, it can also damage the console if you don't take careful steps. A few mods require the use of a "modchip," a special chip that you must buy and insert manually into the console.
The PS2 Simple Media Solution, or SMS, allows its users to play DivX files from their PS2. It also provides support for mp3 files, since the PS2 without hacks can only play audio CDs. This hack requires the use of a modchip for Slim PS2's.
The UsbExtreme differs from other hacks in that you must purchase it. It allows you to run games from a hard drive connected to the USB ports on the PS2. It works via software that you must install onto your computer in order to properly format your USB drive or external hard drive. Since this hack does nothing to your actual PS2 it will not void the warranty.
The uLaunchELF is a homebrew launcher intended to replace the standard PS2 menu. From this new launcher, you can do many things like view images, write text, organize save files, connect to a network or hard drive, or even launch other programs. It is booted via a CD image which you must download and burn.