Green Sponsorship Ideas and Give-Aways

Here are some ideas for brand-able green giveaways and promotional products:

Reusable water bottles
Shopping bags (if you have a bag for the conference, consider a larger size as an option for people who want to reuse it for shopping?)
LED nightlights
Shower timers

One of my favorite possibilities is to forgo the junk and find an engaged way to let people spend your money on their favorite cause: set up a few bins for different charities and give each attendee a poker chip to donate $1 to the charity of your choice, or even collect their business cards.