URI's for processes, stocks, file hashes, UPC's, etc..

Hi,

My company (www.lijit.com) allows people to enter comments about URI's. 
Till now we've only had commenting about URL's, but we have tools now 
for handling comments on stock symbols, UPC/GTIN codes, and file hashes. 
The question then is how to encode these in URI's.

Others have suggested building off our company URL, eg:
http://www.lijit.com/stocks/nasdaq/GOOG
but this won't work because we want this to be an open standard that 
other people can use without tying everything back to us.

I'm thinking of something like:

stocks
security://nasdaq/stock/GOOG

UPC/GTIN
gtin://97807868684494

file hash:
hash://sha-1/2fd4e1c67a2d28fced849ee1bb76e7391b93eb12

I realize these aren't registered schemes. However, will this work, or 
are there any suggestions for a better way to do this?

-stan