Really like what they do at Sussex Cricket ground; you pay a £1 deposit on a beer for the plastic "glass" it comes in. Take it back and get your £1 returned. At end of cricket match there are hordes of kids going around collecting them up to earn some cash. Pretty easy for the kids to get £20+ each and keeps waste levels and staff time down. Glasses all then get cleaned for next time.
Bloody hell you could make an absolute killing on the Western Terrace at Headingley if they did that there.