We have a cheap WiFi home based system that uses motion and sound detection to store to Dropbox (internet disc) or local PC with four cameras cover for front, back and garage.
Philips Insight. Each camera just needs WiFi and a small USB charger to drive it. There is a great iPad/iPhone application as well as a Cloud service for remote monitoring. It takes a snapshot and video clip based on movement criteria you set then pushes it up the wifi/broadband off site so if your home computer is taken you still have the photo/video evidence.
As mentioned it is great for catching the gardener taking the mick. If you tweak the settings it works surprisingly well.
Thoughts to consider.
1. If you want night time cover then look for units with LED's on the front as they will paint the darkness and give some (reduced accuracy) visibility.
2. Most of the home cameras are okay at short distance but if you want to cover to the end of a drive you need a more professional unit like Lillin with a good lens, this becomes expensive. Also the software is used to being installed by a pro and so is more fussy and less user friendly.
3. The WiFi based units can throw a decent connection range but you need the access point in range which can be difficult in old homes with thick walls. Bluetooth is not fast enough or long enough range to do anything useful.
4. Please note that it is quite easy to block WiFi signal and so transmission so this does represent a risk, keep a couple on UTP/Ethernet if possible if you are protecting something of value. If the person listens to the local WiFi and then just sets up a heavy transfer on the same channel it can block the cameras ability to transfer its images.
Hope these help.
