This is a bit late for you, but there is the Mobile ME service from Apple. One of the features there is locating a lost phone; using the GPS and google maps, it shows you were the phone is. You can also send a message to the screen about how to contact you.
http://www.apple.com/mobileme/whats-new/
I think labelling stuff makes a lot of sense though I have not done it myself. However when I met a friend for dinner recently, we ate at a food court, then she was wanting to get to an exhibition so jumped up, and I ran off after her.
Two MRT stations and some walking later she gets a call. Turns out she left her laptop on the chair at the food court. A lady had seen us there, seen the bright coloured laptop case, then saw we were gone, but just thought we were "Choping" the seat!
After a while she realised we were not coming back. She opened the laptop cover; no label! Took out the laptop; no label! Opened the laptop; no password! The laptop springs to life and open on the screen is my friend's grant application complete with name and phone number!
This lovely woman then gave my friend a call and we went racing back to get it.
She is so so lucky. I still cannot believe how fortunate she was. I have to label my stuff before I get complacent again! :">