Why you should curate an Etsy Treasury:
It's fun to do! First you need to come up with an idea of what to feature. Sometimes that comes out of finding one thing that you really love and either wanting to see more of the same or thinking about what might go with that item. Most people like to put together all of one color. I just did one featuring orange paisley.
You're paying it forward. People will want to check out these items and then the shops from which they came. Featuring other shop's merchandise puts out good karma, sixteen spaces worth! When the sellers you feature do their own treasuries, they may come looking in your shop to see if you have an item that fits their theme. Plus, there's all this interacting going on, people visiting other people's shops. It's a good thing (to quote Martha.)
It's easy. Once you get an idea, make use of Etsy's new relevancy search and start collecting listings that fit your theme. All you need do is copy the listing number of an item and then paste it into the little box in one of your sixteen spots. The picture of the item comes up automatically.
It looks really cool all put together. Once you get it done, you can brag about it on Twitter, Facebook, your blog and anywhere else that you have an online presence.