Update May 2009: Craigslist is still the go-to site for local second-hand bargains. Just don't expect to find ads for erotic services; the site has pulled them in reponse to recent controversy.
A yard sale has its shortcomings. What if you don't have a lot of items, don't want to sit by your garage all day, or depend on local neighbors as your customers? A good alternative is to make use of Craigslist, which has become a great internet site for buying and selling almost anything legal- furniture, bicycles, musical equipment, housewares, art, and whatever. Over 40 million people use it every month.
I have a Craigslist purchase in my family room, a handsome chair and footstool that probably would sell for $300 new. I paid a third of that to a family on the other side of town, via an ad on Craigslist. Each fair-sized community has its own place on Craigslist, where sellers can post goods (free of charge) for sale. Unlike Ebay, Craigslist only acts to hook you up with the seller; it does not take a role in the transaction. And since most transactions are local, they are done face to face, reducing the chance for fraud or misleading offers. SInce the deals are done in person, you get your money immediately, unlike the Ebay process.
Take a look at your community's Craigslist to get a sense of the going prices for various goods. You may even see items for sale that you never considered turning into cash. With the economic slump, I've seen a large boost in Craigslist sellers, so be persistent. Those who keep reposting their sales items are the ones that make out best.
Of course, you know better than to take personal checks and the like, right? Demand cash, don't sell to anyone who asks that you ship your goods to them. Take the cash and smile.