We have had the chance to cover many T4i accessories here in the past. It is one of the best pound for pound DSLRs around. It does not have an unlimited battery life though. Thanks to these battery grips, you not only get to enhance your grip but also take more shots with your DSLR:
Canon BG-E8 Battery Grip for Canon T2i, T3i and T4i: the official battery grip for T4i and T3i. It holds battery packs and improves your grip on your camera.
Photive Battery Grip for Canon EOS Rebel T4i, T3i, T2i: holds 2 LP-E8 Batteries or 6 AA’s. You can get up to 3000 shots on a single charge with this.
LCD Timer Battery Grip for Canon T3i: holds 6 AA batteries or 2 LP-E8 Li-ion batteries. It also has clock and stopwatch settings. Comes with vertical-grip shutter-release button and AF-on button.
These battery grips make handling your camera easier and add to its battery life. They are not cheap but great for serious photographers.