I like the idea of IP based webcams that can exist without being connected to a PC, but they are still fairly expensive. I’ve always thought that it must be fairly simple to use an old mobile phone and create a remote webcam using it’s inbuilt camera. Hopefully you would be able to place the phone anywhere and use it’s inbuilt battery to send pics to the web – ideally using WiFi, but also using GPRS or 3G if required. The only limitation would be the battery life of the phone and pluging it into a power socket or car 12v battery/solar panel may still be possible, even if the location is remote (greenhouse, garage, log cabin 
After a tweet from @chilliupnorth I found the software solution … WebCamera Plus- Use your PDA/Smartphone as webcam. I gave it a test and found it worked really well – it also streams live video from the phone directly to the serving machine (which can then re-distribute back out to the internet)
If you are are simply interested in a wireless camera that requires a power socket then check out some of these:
Here are a couple of screenshots of a great iPhone app called Live Cams from @barryegerter. You can use it to link to your own IP cam and control the pan, zoom and tilt in private or you can connect to a massive list of public cams and take control!
About Richard Mackney