Best Tracking Device?

I have just purchased a few very expensive items including a downhill racing bike worth a pretty penny. I am looking to purchase a tracking device that is small and reliable, and that will allow me to track from my iphone preferably but will accept tracking software standalone or over wi-fi.

Can anyone please give suggestions?

You mean (GSM/CDMA) or GPS? Wifi isn't good for tracking.


Some trackers

http://www.voovashop.com/products/1631/

http://www.consumersupermall.com/microtracker-ii-worlds-smallest-live-gps-tracking-device-p-29218.html?zenid=0a8b4ef36a62e866c9275369f5c7f7da

best tracking "device" ever and it comes with fancy packaging: