"The Waiter's Friend" ($3) Pros: Great price (if you can't find one that's free); fast action. Cons: Requires more effort in the wrist; using the blade to cut foil isn't always tidy.
Metrokane's "The Rabbit" ($80) (212-759-6262) Pros: Looks like something M might make for James Bond; cork comes off the screw quickly. Cons: Directions required; pricey, considering it doesn't have a foil cutter.
Trudeau's "Trulever" ($80) (800-878-3328) Pros: Sits on the countertop, so it's hard to lose; cork comes off the screw easily. Cons: Cutter mangles the foil; directions necessary but poorly translated.