This may sound odd, but I use Lansinoh on my lips (and cuticles, actually). I got turned onto it when I was nursing my daughter; it's actually for sore, chapped nipples. But the stuff is absolutely fantastic for lips, too. It's a thick emollient, no taste and stays put. I've recommended it to so many people and they love it. You can find it in Target in the newborn product section and it lasts forever. Excellent reviews, too:
http://www.amazon.com/Lansinoh-HPA-Lanolin-2-oz/dp/B0018D...
I'd stay clear of the petroleum-based products like vaseline and aquaphor, personally.
Added: (you'll notice in the reviews that many moms also use it for chapped lips!)