File based locking. If you want to write something to the database file and something else is writing there (User stats, logs, new blog), the database just gives you an error instead of a database connection.

I went for a pretty tiny install of a webapp with SQLite, figuring being the only user, what can go wrong, but had to migrate to postgres pretty soon because I kept getting errors when my actions clashed with one of the background task (that ran every 15 minutes).