The Powabyke Commuter is an electric bike designed with commuters in mind. It sells for around $1700 in the U.S., which about what you can expect to pay for a quality electric bike. I had the opportunity of trying this bike, while visiting the Green Festival in Washington DC. The Powabyke's acceleration was quite smooth, and the motor certainly seemed powerful enough to get you up those hills. The bike has two modes: "power assist" mode where you assist with the pedals, and "power only" mode, where the bike runs solely on the electric motor. The range of the bike in "power assist" mode is 34 miles, and 20 miles in "power only" mode.
The Powabyke Commuter has 24 Shimano gears, a 200 watt power output DC brushed front motor. It takes eight hours to fully charge the lead-acid batteries.
The bike I tested was courtesy of a dealership called Powerbyke USA in Virginia (thanks guys, you were very helpful).
There a number of other Powabykes models including an electric tricycle with a storage compartment.
There are photos and videos of Powabykes on this page.