For TiVo users, TiVo's iOS app makes a convincing argument for having a dedicated iPad for your living room. As of today, you can also say it makes a strong case for buying a Kindle Fire, as the same app is now available for Android devices.
In a nutshell, the TiVo app--which works with smartphones and tablets--lets you control, search, browse, explore, and comment on Facebook and Twitter all without interrupting the programming currently playing on your TiVo box. (Checkto see all that it can do.)
All you need to do to get it up and running is download the free app from the Android market, connect to the network your TiVo is on, and enter your Media Access Key, which you can get from your online account info or from your TiVo's settings menus.
Overall, I find the experience and control better with the apps than using the RF or Bluetooth remotes and the TiVo box's interface, which I guess isn't the best thing for TiVo users without an Android or iOS device.