Jailbreak

Ultrasn0w – unlock almost any iPhone. This tool will unlock your iPhone to all networks.

Yellowsn0w – unlock your iPhone 2G and iPhone 3G up to firmware 2.2. This is an unlock only tool and will unlock your iPhone to all networks. Now replaced by redsn0w.

Redsn0w – unlock and jailbreak your iPhone 2G, iPhone 3G, iPhone 3G S, iPod Touch, and any firmware 3.0 device. This multi-function tool is only for those who have not already unlocked their iPhone with yellowsn0w.

iPhone 3G S unlock – See Redsn0w (above), or check out this alternative unlock from Purplerain.com. Both apparently work, although redsn0w is supposedly more stable for unlocking your iPhone 3G S.

Blackra1n or Blacksn0w – simple jailbreak and unlock for the iPhone 3G and iPhone 3GS

Untethered Jailbreak – 100% software based jailbreak for the iPhone and will also jailbreak the iPad