Craigslist

craigslist.org is about
from Mission and History website page
 * giving each other a break, getting the word out about everyday, real-world stuff.
 * restoring the human voice to the Internet, in a humane, non-commercial environment.
 * keeping things simple, common-sense, down-to-earth, honest, very real.
 * providing an alternative to impersonal, big-media sites.
 * being inclusive, giving a voice to the disenfranchised, democratizing ...
 * being a collection of communities with similar spirit, not a single monolithic entity.

See if your country/province/state has a local Craigslist.

People are offering, trading and also giving away free services/products on there all the time.

Be aware of charlattans.

Related:
 * Best posts of CL <--funny
 * Social_software