I started selling books on half.com in 2001. It came about when my husband and I noticed that profs at the university where I taught left stacks of books outside their doors, free for the taking every quarter. Of course, without the iPhones and cells we have now, I couldn’t look up the selling price on the spot, so we took books that looked interesting and checked online at home. Over a year or so, we made well over $1000 on used books. Now, however, there is so much competition, not to mention fees, that I no longer sell, but I applaud those with the energy and tenacity to make that option profitable.