BlowSearch: Another Little Engine That Can

I saw a post by Danny Sullivan from a few days ago praising BlowSearch for allowing source exclusion. Thinking this was some method of countering false clicks or some other counter to dynamically generated code I dropped by - especially since I am also an advertiser.
While one of the possible benefits of their relatively new offering is lessening of Click Fraud, more importantly you can exclude your competitors from seeing your ad - thus not letting them click on it - but also not allowing them to just see the copy if they are copying... let them move on to a lesser competitor.
I will be playing with this and let people know how effectively it works.