The HyperMac External Battery. If for whatever reason you need your Mac to be turned on for 32 hours straight then this is for you. Be warned though, the thing looks like an aluminium brick and is just as portable.
The 222Wh unit can keep you going for ages and the external HyperMac External Battery charging unit also comes in a 60Wh version for $200, a 100Wh for $300 and a 150Wh for $400. The price of the 222Wh version is a stonking $500. HyperMac must have gotten the impression form somewhere that Apple Mac owners have money to burn (or to spend on a HyperMac External Battery).