The new Locator from British firm Acutrac will send you position and status alerts by text and/or email, but (unlike many other tracking devices) there's no monthly subscription fees, so the only additional charges are for text alerts.
Owners can track the movement or position of their bike using a password-protected website. The Locator can be programmed to send a position report every minute/hour/day while the bike is moving.
Alternatively, it can be instructed to alert the owner only if the vehicle moves into or out of a pre-set area (called a GeoFence).
The Locator is apparently simple to fit, too. It connects to your battery with just two wires, and it doesn't matter which way round you connect them.
It sells for £299.99, which includes a three-year network subscription.
More info: 01264-310007 or www.acumen-electronics.co.uk