If your old iPhone's been sitting neglected on your desk since you upgraded to a shiny new iPhone 4, you're not taking full advantage of the exceptionally capable handheld device you still have at your disposal. That old iPhone may not have all the same raw power, but you'll still want to keep it around to take advantage of apps and functions that help you in your home. Plus, even without a cell plan, you can keep it as a backup to make calls. Here are three uses for the still-viable gadget.
The Ultimate Remote
You can employ an iPhone as a remote for nearly any piece of electronic equipment, and it's extra convenient to keep your old one on your coffee table for whatever you need to control. Besides TVs and Blu-ray players, you can get apps for both the Boxee and XBMC media centers and control iTunes with Apple's free Remote app. Even better, you can pair Remote with an Airport Express Wi-Fi router to control an inexpensive multi-room wireless music system. And if you're a photography hobbyist with $20 to burn, use your iPhone as a remote shutter for your Canon or Nikon DSLR camera and wirelessly review images with the DSLR Camera Remote app.
When you're not using it to flip channels or put on music, the iPhone also makes an excellent webcam. It costs less than buying a new one, and it doesn't have to stay next to your computer or be set up in one place at all times. With the iWebcamera iPhone app ($5; itunes.apple.com) and the accompanying desktop drivers for Windows or Mac (free; drahtwerk.biz), you can tether your old iPhone's camera to your computer to create a live video stream that works with any webcam-enabled application, including Skype and YouTube. It works wirelessly as long as your iPhone is connected to the same network as your computer, and it's simple to set up.
A Second Line
Download Line2, an app that adds a working line to your old iPhone. For $10 a month, you get unlimited VoIP calling and text-messaging over a Wi-Fi connection. Sure, you can run Line2 on your iPhone 4, but it's handy to have a number for people you don't want bothering you on your regular line. If you're already a Skype user, get a dedicated SkypeIn phone number ($60/ year; skype.com) instead. The extra line lets you save your active iPhone's battery and minutes. And if you plug your two numbers into Google Voice (free; google.com/voice), when people call you at home, both iPhones will ring, so you can manage your minutes by choosing which one to answer.