1. MapQuest (10.98 percent)
2. Google Maps (9.81 percent)
3. Southwest Airlines (3.31 percent)
4. Expedia (3.02 percent)
5. Yahoo! Maps (2.97 percent)
6. Travelocity (1.99 percent)
7. Orbitz (1.60 percent)
8. Yahoo! Travel (1.56 percent)
9. Priceline.com (1.53 percent)
10. American Airlines (1.23 percent)

Link

From what I hear the people that work on that Southwest Airlines website are pretty darn cool, but that hasn’t been confirmed.