If you have an older smart phone laying around, put it to use or sell it. How about a security or baby cam?
With software use the phone as a security camera. I have a little windshielf suction holder for the phone that I set on the desk with the camera facing a desirable direction. Then I use FREE software to take a silent photo if the phone notices movement. The photo is then e-mailed to me for viewing as well as stored on a private web site. Here are some software titles for this purpose. Motion Spy Camera or Spy Camera OS for Android and SpyCam, Motion Detector Pro, Bodyguard Pro for iOS.
Tip: Have a place for the phone where it can be charged and always available.
If you don't want to or can't sell the phone, either give it to someone or put it to some use. I've found a few chores my old phone can still do and do nicely.
Put a few games on it and let the grand kids play. Even though the phone might not be able to make calls (mine cannot) it can still connect to WiFi and I put a few games on it and it's always charged up and ready for the kids. Oh, and don't forget to have a pair of ear buds to keep things silent too.
Connect speakers to it and use it to play music. Since there is quite a bit of space on the older phone as I don't have that many apps on it, there is loads of room for music. 1 GB can accommodate over 100 songs so it works nicely.
Use the phone as an extra camera. It's always nice to just grab this phone to take pictures. I have the phone automatically upload photos to Dropbox where I sort or discard as needed. This way I never have to remove the memory card or deal with e-mailing photos.
Share your smart phone uses in the comments and I'll share with everyone.