To control the Roku you can use the included remote control, or an app running on an Android or iOS device, which control the Roku over Wi-Fi rather than infrared so line-of-sight is not required. Some of the current Roku apps for Android:
- Roku (official)
Works well, but requires you to sign in to a Roku account, so can't be used to control a Roku without access to the Roku account. - RoByte - Remote for Roku
Works well. Recommended. - Rfi - remote for Roku players
Automatic scanning fails to find the Roku XDs, and a pain to set up manually. - Remote for Roku
Lags after touching controls can make it hard to control a Roku properly.
Perhaps the best alternative to Roku as of this writing is VIZIO Co-Star, a 2nd-generation Google TV box that's similar to Roku. Pros include the more sophisticated Android platform, wealth of Android apps, Chrome Internet browsing, 3D support, DLNA, and HDMI pass-through. Cons include greater complexity, lower maturity, blocking of some content, clunky remote, and less smooth interface. Google TV devices will likely continue to improve.
Update (January 7, 2013): Another promising Google TV alternative to Roku is the new NETGEAR NeoTV PRIME.