iTaggit

One site that takes advantage of the digital archiving or "online collection" approach is iTaggit. You have the option of keeping your items private or sharing the details of your collections with the world. By signing up for a free account, you can easily meet fellow packrats who might share your same zest for amassing curiosities, like misprinted Disney collectibles. You can also discuss values, and negotiate trades. There are also resources on collecting various items, including forums and "expert" blogs.

This may very well be the first social media site that I have discovered that connects individuals based on what kind (and how much) "stuff" you have. On the surface it may seem a bit shallow, but it's all in good fun. The layout has something of an "Ebay" feel to it, and seems easy to navigate.