I discovered thrift shops in college, when a friend and I had a informal business buying, refurbishing, and reselling violins, mandolins, guitars, and the occasional dobro. My first apartment in New Haven was furnished from thrift shops and tag sales (known as yard sales or garage sales in the Northwest).
I still love to spend Saturdays at yard sales, and results from my favorite eBay searches are emailed to me every night. My wardrobe is a mix of Eddie Bauer, J. Jill, eBay and the local consignment shop; the decorative aspects of our home furnishings (pillows, tablecloths, lamps, paintings, bookshelves, and small tables) have decidedly non-retail origins.
Amazingly, there are people even more wrapped up in treasure hunting than I am. One of the blogs I follow is written by a semi-professional young thrifter. It appears she struck gold at the local Goodwill store this week. Very cool.