We personally don't have Direct TV, but for those of you who do, take advantage of the Direct TV iPhone App. It gives you 'round-the-clock, portable access to your Direct TV DVR account.
That means you can set new recordings or cancel existing ones from anywhere. Forgot that the CMAs were on before you left for the movies? Just set a new recording and catch it when you get home. Watching Top Chef at a friend's place? Stop your own taping and save some room—no need to go into entertainment debt!
The app is free! Even if you're not a Direct TV user, it might be worth the "money" to download this app for the ability to search current show guides and read episode information and summaries.