It's trivially easy to copy a SQLite database. It's less trivial to do this in a way that won't corrupt it. Here's how:
shell$ sqlite3 some.db sqlite> begin immediate; <press CTRL+Z> shell$ cp some.db some.db.backup shell$ exit sqlite> rollback;
This will give you a nice clean backup that's sure to be in a proper state, since writing to the database half-way through your copying process is impossible.
Thanks to Habbie for this info!