Add a "cool listings"/"my finds" feature

[audiodude]

Two main problems with adding this feature, which simply allows you to "favorite" or "save" an item and come back to a page of all your saved items.

1. If we add this, we're going to need a datastore of some kind. Sqlite will probably do at the scale we're currently at. If we start with sqlite, it should be easy enough to move to MySQL at some point.
2. I imagine users will want to save their selections for more than their immediate browser session. This leads to a discussion on whether and what kind of authentication system we want to implement.

Otherwise it should be pretty straightforward. It would need some kind of basic design though.