If the big boys were able (which they may) to develop relationships with the client like OO's can they would rule. I believe the client likes knowing who they are dealing with. They have trust and faith that they will be taken care of. I doubt they let you in and leave blank checks to be filled...
I do send out reminder cards to every customer every six months. I noticed that some of my repeats were trying to use the gift cards after the expiration date. Being in the northeast I was trying to drum up more work during the winter months.
If you're doing this to get the phone to ring I don't think a $5 dollar box of cookies would make me want to call. If it's strictly for a good will gesture then that's another thing. It never hurts to support local organizations