Got to keep your eye on that eternal 's' debate.
Quizpal.com is taken. It's just a parked page with some ppc banners on it, but it's getting a little traffic. If it's just the name-sale you want, in this case I'd say their singular beats out your plural hands down.
However, if you know what you're doing, it's all about traffic: you can have the last laugh, and the bigger dollar, if you know the tricks for how to get more traffic to your site than they do.