You might inquire through your bike shop, the Salvation Army, other caring agencies... or even the Yellow Pages.

In Montréal, we have one firm that recycles bikes either for lawn ornaments or for cheap second hand bikes (depending on their original condition), another group that gathers used bikes to send decent bikes to Cuba (to be used as bicycles -- we are in Canada, BTW) and another group that sends used bikes to various African and Latin American countries, both to be used as bicycles or as machinery. All these groups are local