We have a local Yahoo "FreeCycle" page and Ive given away lots of stuff thru this. Mac stuff, kids bikes, boat stuff, sports equip, just about everything. It has to be free, and you also can post for wanted stuff.
Also I have donated lots of stuff to our local schools. I live near the gal who runs the graphic arts dept at our local high school, and she will take anything from MacWorld magazines to software, and anything that works well. Not too outdated though.
Some of her students are needy, so anything that will help them is good.
There is also a retired doctor who fixes PC and Windows stuff and donates it to the school too.
Jane