Funny you should mention this. Just today, I stopped at the bakery and bought a big sack of home made cookies for the mechanic (who is also the owner) of a small local shop. Awhile ago, he resolved a tech issue in a very creative way, and I've been meaning to tell him thanks. I would have brought beer, but he has some teenagers working in the shop, and I didn't want to cause any problems. It wasn't exactly a tip, but I think it created a good vibe.