Due to local ordinance, the stores here have to charge for paper bags - no plastic allowed anymore - so a lot of people don't ask for them or bring their own bags. Thus they've become a bit of a treasured resource for me. (I still miss the plastic grocery bags because I used them as trash can liners. I used up the last of my old hoard earlier this year and was sad.)
I usually use them to take stuff to the thrift store, carrying presents to friends, etc., and recycle them when they start falling apart. Your local thrift stores may be happy to take them as well, to give out with purchases. I know ours do.
