Nope, there isn't one as good.
But the good thing about Little Snitch is that you can use it without a license, you just have to re-start the network monitor every 3 hours. Apart from that, it works just like the full app.
I bought the full version and it's *still* stopping every three hours, and nothing I've tried will make it work right. It won't let me re-enter the serial or anything like that. Maybe it's because I had the demo version installed first and upgraded from there?