The joy of giving
Craigslist is a strange information ecosystem: it's a place where strangers reach out to one another to offer free washing machines or spare rooms or anal sex. I don't look at it very often, but I am always fascinated by the stuff people are giving away for free, and the stipulations they sometimes put on it (must be a mother in need; must provide transportation; must take all of the issues in my Maxim collection). The stipulations are just a further development of the impulse that drives one to list something to give away rather than simply putting it in the trash. Because one bought something in the first place, one invests it with value that one then hates to see wasted or destroyed. "If I bought it, it must be worth something" -- the objects take on ego value, and throwing the stuff away would be like killing a part of yourself. But on the other hand, purging ourselves of unnecessary things is one of the great joys of living in an affluent, materialistic society, almost as pleasurable as acquiring luxury goods in the first place. Perhaps it's generational and geographical to a degree (tiny NYC apartments), but most everyone I know longs to get rid of stuff, to streamline their lives, to get rid of the consumerist barnacles that have attached to their lives so as to better use the things that are "really essential." Thus we become preoccupied with the cyclical waxing and waning of our possessions, and we try to recruit others to share our primary fascination with our collection of junk by offering them some of it for free.
Of course if one has more time and energy, one can introduce market forces into the ebb and flow of one's belongings by turning one's life into a permanent yard sale, auctioning items perpetually on eBay (to some degree Craigslist's evil cousin). This allows the market to affirm the value of the things you no longer want but once did, it puts a price tag on that memory and allows you to let go of the material thing to which that price is attached. Someone on eBay pays the ransom, and you've happily shed one more barnacle without having to feel like you were ever a sucker along the way, buying something you didn't really need. The Craigslist giveaway earns you a different peace of mind, that you have somehow transcended money; you paid in the stuff you've shed for that feeling of being nonmaterialistic, outside economics. (But there is no "outside" of economics, as all behavior can be thought of in terms of incentives.)
The giveaways may also be an attempt to build community, to invoke an ethos of sharing in the face of the dominant ethos of hoarding and competitive acquisition. At some levels it may even turn into a potlatch of competitive giving -- you're giving a toaster away? Well, I'll give a microwave. Giving something away can serve as a pretense for meeting someone, a good faith gesture that invites reciprocation, but that runs counter to the ideology that true friendship is gratutitous, coming with no strings attached. But still, it seems liberating to stop piling the mountain of goods between ourselves and other people and begin to dismantle it by giving that stuff away. Too bad it just piles up somewhere else.