http://www.eurocointracker.com" onclick="window.open(this.href);return false; ?
We produce round stickers and add them on the bigger coins. 2 Euro , 1 Euro , 50 Cent
On the sticker is the url and your own printed code..
Preproduced by a database
For Instance my name Eef would be first three of the code.
Then a 8-digit serial random by computer, with letters in it.
So on the sticker it just says >
http://www.eurocointracker.com" onclick="window.open(this.href);return false;
EEF15H1J98U
You put the sticker on the coin.
Enter it in a database
And wait until someone else enters the coin..
Would it be legal to put this on a coin?
of course, sticker has to be from thin and good glu-ing material..
I think that's at least crazy!! 
Not to say that it might not be legal. 
