iFaith is a Windows program that can get SHSHs on your device, rather than from Apple's servers. This lets you keep the device on whatever firmware it's currently on (e.g.- iOS 4.2.6).
iFaith can also build an IPSW that's already configured with your SHSHs, and will also upload your saved SHSH to a remote server for backup purposes.
by iH8sn0w.