You could have an office party and consider making some of these great items, all designed with the same idea in mind - keeping samples out of landfills.
http://www.amplesample.net/2008/entries/
The slippers are pretty fantastic and several of the conceptual ideas ought to be brought to life! Maybe you can create some stools or tables for office use. Instructions are included for the winners, but most of them seem simple enough to figure out. Or perhaps someone around your place could come up with next year's winning design...? You have until April :)

An animal shelter would be a possible candidate - especially with the pet bed instructions included, and even thrift stores can resell things like samples for someone else to come along and find a use for. A youth group might turn them into something they could use in-house, or sell for a fundraiser.

Best of luck finding them a home, and thanks for being mindful of the waste.

I remember sitting on carpet samples both in elementary school (gym class and to sit on so we didn't sit on the vinyl floor) and at the public library during storytime. Maybe ask your local Girl Scouts or Camp Fire if they can use them (like at campgrounds as mats so you don't sit in the dirt).

And TrixieDelicious is right that they'd be great for an animal shelter (think cat platforms).

Why not offer them up free on CraigsList or Freecycle? I've seen carpet remnants and samples snapped up very quickly on Freecycle. People use them for their houses (I know one woman who has entire rooms carpeted with small samples - she runs a in home daycare), shops, or for projects like cat towers, etc.

I'm thinking that the Boys and Girls Clubs or other similar publicly funded community centers might be very grateful for the carpet.

Similar to Shanna Lee, I suggest checking with your local park district or city parks system. Youth or preschool programs can use them as squares for kids to sit on.

It depends on where you are, but www.carpetrecovery.org is a good place to start.

If you're in Austin, I posted a list of where to recycle "difficult" things at www.livinghouseaustin.com - although that website isn't going to be up much longer, as I agreed to merge it into Austin Eco Network's...For carpet, look for G & R - it's free and they take the carpet padding too.

Where are you located? We are a non-profit in the mid-west and we could offer an in-kind donation form for tax purposes if the carpet was donated. http://www.gointernational.tv

iReuse is a great service in California:
http://www.ireuse.com/

You get rid of stuff, and the stuff goes to nonprofits. Yay!

You could donate them to a college's Interior Design program. When I was in school, we had lots of fabric samples, but our carpet selection was very limited.

I think you're already on the right track. Build It Green is an awesome place to donate to.

Maybe Salvation Army? You can schedule their truck pick ups.

We've given carpet to the Humane Society, and carpet and all sorts of other samples (laminate chips, wall paper books, wood finish samples) to Head Start.

i'll try to remember head start for next time. a lot of the other places mentioned did not accept samples :/

You don't mention where you are, but Zero Landfill in Cleveland takes stuff like this and redistributes it free to teachers and artists for use in classrooms and artwork.
http://www.zerolandfill.net/

maybe donate them to an interior design programs' materials library, like the one at the University of Florida where I attend.