Not coincidentally, this library is intended to mimic the functionality of CouchDB on the client-side, and may even support integration with CouchDB in the future.
Things to do
To learn how to use BrowserCouch, check out the work-in-progress tutorial.
Aside from that, you can run the test suite and the semi-large data set test, though they're not particularly exciting. In the future, we'd like to make CouchDB's Futon client work entirely using BrowserCouch as its backend instead of a CouchDB server, but that's a ways away.
If you'd like to see more code samples of what the BrowserCouch API currently looks like, check out the annotated source code for the test suite. You can also read the primary source code documentation for more on BrowserCouch's implementation.