Share your collection with Kollecta
Once you've created a profile with all of your stuff you can join a group and share that list with other collectors on the site. Users in the group can talk about their passion for coins, stamps, smurfs, or whatever else it is you're collecting, rate items value, share collecting tips, and arrange to buy, sell, or trade items with others.
Providing what you collect is in Kollecta's database, the site could be a good place to keep track of your collection and connect with people who can help you add to it. If what you collect isn't in their database, or there isn't a group for it yet Kollecta provides you tools to add them.
Kollecta is currently free, with mention on the site of a potential cost later down the road. A similar site for collectors is iTaggit.