My school is participating in a nation-wide recycling competition among colleges and universities called RecycleMania.  Each week, we've picked a theme to promote recycling, waste-reduction, environmentalism, etc.  

One week was "close-the-loop" and we emphasized the reuse aspect of the recycling slogan by doing crafts from used carpet and books.  

Last week was "Salvation Style" and we ran a clothing drive, and WERE going to have a used clothing fashion show.

Next week is "Kiss Me I'm Green" week.  We are going to have a kissing booth in our student union for those who recycle at our table.  It might be germy, but at least we'll be getting people to recycle.

Just some ideas :o).

...at the University of Washington (go, Huskies!), a dozen and a half of us organized a campus-wide Earth Day (I think it was #17 of the annual series).  

The theme was, "Toward Environmental Sustainability".  I continue to believe it was apt and prescient.  Communicating a sense of action/movement is good.  We wanted to get everyone involved in working toward this common goal, hopefully all year round and not just on this one day or week.

A bigger challenge will be be to define specifically in the context of your work and company's mission and goals, what moving toward sustainability means.  And then see about doing those things in real time, all year long.  

Good luck!

I am not sure if this one will help you, but I love it.
"We do not inherit the earth from our ancestors, we borrow it from our children". Indian proverb.