Free stuff for the designated driver

At sports arenas (most of them, in my experience), festivals and events where alcohol's served, and at many bars and clubs, you can identify yourself as a designated driver and receive free soda(s) and/or other perks.  Often it's not well-publicized, but keep your eyes out, and when in doubt it doesn't hurt to ask.  A "guest services" booth is typically the place to go.

The restrictions on this sort of thing are usually pretty lax (at least at big events or arenas; I imagine bars would be more observant)-- show your drivers license, get a free drink ticket-- so there's lots of potential to stretch the system.  There's kind of a spectrum: from the genuine designated driver who'd certainly be drinking along with his/her friends if he/she wasn't the DD this time... all the way to the group of friends in a single car who all register as designated drivers, get their sodas and/or other loot, and then go ahead and drink alcohol anyway.  Figure out what you feel comfortable with ethically.  (The way we usually do it is that only the driver of the group signs up-- but it's okay for him/her to do it even if he/she wouldn't've been drinking in the first place.)

So that's my tip of the day. It's a nice freebie that's easy to miss-- let your conscience be your guide.