Allowing customers to download their photos at a later time

[whataparty]

Hey guys! I have a small novelty photo business - I take lots of pictures that people buy on-site - but am looking to allow for these people to go to my web site at a later date - and purchase larger pics, keychains, etc.....I am using printroom.com to facilitate this (if there are better services I would love to hear about them) - but my problem is - at some events I can take hundreds of pics - and I do not have a system where people can come to my site on printroom.com and just quickly locate their picture. Basically, the user needs to look thru all the pics I have posted until they find their own.

Ideally, I would like to give each person a number or code at the time of purchase, so they can later hit my web site and search for their pic. Is there software or some sort of system that makes this easy?

Any feedback would be greatly appreciated. This would help my business tremendously.