How to keep an eye on a room when I'm not in the house?

I need to keep a lookout in the living room of my house as I'm having work done but won't be there to oversee it, but I don't really want them to know I'm keeping an eye on them. Is there an app or free bit of software that lets me keep an eye out, or record either sound or footage of the room to review later?

I have a laptop with a webcam, an ipod touch (with no camera or sound recording) and an iphone 4s available to use.

Any help?

Many thanks

Added (1). The Laptop also has a built in microphone

I let you choose which one. There's five, some of them only run be detecting movement in the room. Nearly all Laptops have a Built in Microphone its got a microphone symbol and a small hole, near the socket you put the External microphone in.

You can set up the web came to facetime your phone, or use websites that allow video chatting, like Skype!

You are not seriously gong to leave the laptop in the room with people you do not trust? Or other expensive equipment? You must be mad. You need to get an IP covert camera, they can be very expensive. That would need to be hidden somewhere and connected to your router, and then you forward a viewing port on the router to the camera. If you want it to record you could get a standard CCTV covert camera and connect it to a recording device designed for the job.

Use iSpy, its a motion detector and records a video when your webcam sees anything thats moving for about 10secs and then stops and starts over again.

Its freeware and comes with a tutorial on video from the help menu

I think Fred is right. The fact that that if anyone comes in, they will either switch off or shut down (for computers) the used appliance, for privacy (without being seen doing it). Otherwise, they will just shut it down (or switch it off) and take it. It just makes the robber happier. Hiding the computer has not much use since the display is huge, and anyway, it takes far more energy to keep the appliance running (also therefore heating up the room, for computers) than to use it as a CCTV camera. Therefore as Fred says, I recommend you buy a CCTV camera itself.