Yesterday, I tripped over the Lawnchair project, which I immediately took a liking to. Here's the description:
A Lawnchair is sorta like a couch except smaller and outside. Perfect for HTML5 mobile apps that need a lightweight, adaptive, simple and elegant persistence solution.
Just like SQLite kinda sorta lets you run SQL, but is in fact an embedded database, Lanwchair lets you play with a NoSQL database while being in a simple embedded environment.
Not sure what project I'll use it for, but I'm eager to play with it.