I have SO many I use, but the ones I use consistently are
5 - Sportacular/ESPN ScoreCenter - I prefer Sportacular, but ScoreCenter allows me to get Ebbsfleet United scores
4 - DirecTV - can set my DVR while I'm traveling in case I forget something
3 - FlightTrack - I travel for work, so it keeps me from wasting time getting to the airport early, or allows me to rebook if there are issues and I know of them ahead of time.
2 - Flight Control - most addictive game ever. Still can't get over 111 on the original airport.
1 - Lose It! - Using this app to track calories and exercise, I lost 55 pounds in 4 months and have stayed at the same weight since, despite three weeks in Barbados/St. Kitts on work. I can actually say that this app changed my life.
Honorable mention -
Monopoly, WeatherBug Elite, Crash Kart, Texas Hold'em, Yo Craps!, Around Me