Etsy treasuries are little collections of items from etsy shops, created by etsy users. They're themed by color or team or topic or lots of other ways. What's the point? Well, they're fun. And also, these collections often end up on the front page of etsy, which is great exposure for the artists in them.
Here are a few of my recent ones. This one was titled etsy vs the bed.
And this one is still active, chicken and waffles.
This one has items from two etsy teams: pcagoe and eart.