www.hdloader.com
Wow. This just came out for the PS2. It allows you to use a HD (official or IDE) and back up PS2 in ISO format to it. From what I've read, it boots games directly from the HD, giving you faster load times, and the ability to play backups without a modchip!
All you need is the HD Loader, A network adapter, and a hard drive. A few games don't work though. PS1 games won't work on it either. But still, this is totally amazing. It costs just under 100 for all the parts, too.