Knowledge of smartphones and PDAs doesn't necessarily equate with parenting experience (it's nice to see a kid learn how to text though), so take this advice with a grain of salt. But if your bundle of joy is sleeping peacefully and you need to get some work done in the next room, WikiHow shows us how to jury-rig a baby monitor. All it involves is placing a phone next to the baby, and calling it with a smartphone. After the call connects, turn on your phone's mute and speakerphone modes, so you'll be able to hear if the baby cries. Without waking it up with noise from your end.

Of course, this is only financially reasonable if you use an unlimited plan to make the call. And the scheme is no license for leaving the baby unattended for extended periods of time, or if you are a significant distance away from it. It also goes without saying that your service provider should have great coverage of both areas.