The Nikon EN-EL3e Rechargeable Lithium-Ion Battery from Lightbulb Rentals provides 7.4V, and can store 1410mAh of power - that translates into over 200 shots on a charge. The battery is compatible with Nikon D50, D70, D70s, D80, D90, D100, D200, D300, D300S, and D700 SLR Digital Cameras.
Sony NP-FW50 Battery (W-Series)$6/day
Sony NP-F960/F970 Battery (L-Series, Large)$15/day
Canon LC-E6 Battery Charger$5/day
Sony BC-U1A AC Battery Charger$12/day
Nikon EN-EL 14 Battery Charger$15/day
Quad Charger: Anton/Bauer, Gold Mount (14.4V Only)$30/day
RED V-Mount Battery: Hyper Core Pro-X (98Wh)$20/day
Canon BG-E11 Battery Grip$29/day