Gotya is an app that can be used to turn a Windows Phone into a smart motion dectection camera (i.e. take a photo when motion is detected). The same app can then be used, on a different device, to remotely control and monitor the camera on the first device. Combined the two devices will form a basic, remotely accessible, personal surveillance system. 

The remote access element of Gotya is enabled by a cloud service, which can also used to stored captured photos online. The service can also be configured to email you  an alert, including a link to the picture in the Gotya cloud, when motion is detected. A stand alone mode is also available, but it is less useful as there's no remote access and captured photos are stored locally.

Gotya provides an opportunity to make an old device that is sitting in a drawer useful again. Some set up is required (e.g. leave the app running, provide external power), and you'll need to work out a mounting system (e.g. tripod), but overall it will still be a lot cheaper and easier than buying and installing a dedicated surveillance system from scratch.

The remote controller element of Gotya lets you view not only the cpatures from remote camera (on demand), but also change the camera settings (e.g. flash on or off, image quality, motion detection sensitivity, whether to save images to the cloud, whether to play an alert sound, and more).

You can add upto four remote cameras (phones) to any account, potentially allowing you to provide coverage of a number of locations, or have multiple camera angles in a single location. The remote control service is also available through a web interface.

The Gotya app and service, in its full incranation, does assume you have a spare Windows Phone device sitting, unused, in a desk drawer. That's not going to apply to everyone, so it is worth noting that the app is also available for Symbian, expanding the pool of devices that can be used as a remote cameras. 

Windows Phone Store description:

Gotya for Windows Phone is your personal and private mobile photo surveillance system. 

Gotya turns your Windows Phones into a smart motion detection camera and remote controller so you can capture pictures of moving objects at home or anyplace else. Detect and take pictures of trespassers or suspicious people, package deliveries, contractors, pets, stray animals, or anything else that moves. 

Use Gotya as a standalone motion detection camera app and capture and store pictures locally on your Windows Phone, sound an alert, and fire the camera's flash when motion is detected. 

Connect the app and cameras to the optional Gotya cloud service for camera remote control including instant snapshots from up to four cameras at once, email alerts with a link to the picture in the Gotya cloud, instant picture alerts, and automatic upload of pictures to the Gotya cloud. Remote control app is also available on the Web at gotya.mobiapplines.com. 

Gotya can be downloaded from the Windows Phone Store. A free trial is available with the full app costing £1.49 / $1.99 / €1.99. In order to get the most out of the app you'll need a subscription to the cloud service (used to store captured photos online), which costs $12 a year. However, for a limited time, a 60 day free trial of of the Gotaya cloud service is available to new users. 

More information on the app and cloud service are available on the Gotaya website.