I'm not sure there is such a thing as `simple' but we have four Foscam model FI8910W tilt/swivel cameras that we use to monitor the inside and outside of our house while we are away. They are connected to the Wifi system in our house (no computer needed) and can be accessed by anything that can get on the internet. We use our smart phone.
The good news is that they work just fine. The bad news is that I have to pay someone to come in to connect it to the wifi system. Something about port forwarding that I refuse to understand.