Hi,
I put a little service called Spootnik (
http://www.spootnik.net) together which synchronizes Basecamp directly with OmniFocus.
It is currently in private beta. If you like to test-drive it you can sign up here
http://www.spootnik.net/signup.html and join the private beta crew. It's always hard to find good private beta astronauts. You're very welcome!
Best regards,
Lars