What kind of camera to use for Robot?

I'm unsure of your exact application or requirements (image quality/FOV/etc) but relatively inexpensive wireless color and black and white cameras are readily available in thwe 900mhz, 1.2ghz and 2.4ghz frequencies (the latter might cause problems with other consumer items that share this frequency). 433mhz video transmitters are also available that don't cost too much; in the US, however, these will require an amateur radio license, so check the applicable laws in your country of origin.

Connect the receiver to a cheap framegrabber card on your computer to do image processing, or directly to a monitor. One major advantage of wireless cams over webcams is that the wireless cams often have a wider FOV, which could be important in some applications.

Using a webcam with an onboard computer and transmitting images back via

802.11b (or a or g) would work well, but expect the images to eat a significant amount of bandwidth at higher framerates if the video is not already compressed.

If your robot already has a controller onboard capable of interfacing with a webcam and supports a wireless LAN, you may find that a webcam is the way to go. If not, consider a wireless camera. You could use either a separate camera and transmitter, or choose a camera with the transmitter already built in.

If you go the wireless route, avoid X10 cameras -- these are among the worst performing cameras on the market.

You could try the new Network TrackerCam

It has a pan/tilt feature that may make it quite interesting for a robot-head.