iDemo is described as 'tool that simplifies real-time demonstrations of iPhone apps and games. iDemo connects to your iPhone over WiFi and mirrors your iPhone screen on your desktop, in real-time – kinda like Steve Jobs during his keynote presentations'. There are four alternatives to iDemo for a variety of platforms, including Windows, Mac, Xbox, Android and iPad. The best alternative is AirServer. It's not free, so if you're looking for a free alternative, you could try Shairport4w. Other great apps like iDemo are Reflector (Paid) and X-Mirage (Paid).
Reflector is an AirPlay receiver that allows you to wirelessly display your phone or tablet on a number of devices. It’s available for Mac, PC and most Android devices. Mirror your device on a big screen without wires or complicated setups.