Auctions add interest to web sites
In addition to the profits that they generate, auctions can add interest to email newsletters and web sites. There's a bit of a voyeur in everyone; people are always interested in what others who share their interests are doing.
The PHoto-Eye bookstore and gallery, www.photoeye.com, in Santa Fe, NM, takes full advantage of this universal drive to find out "what's up?" Their weekly e-mail newsletter lists a variety of rare books and prints that are being auctioned.
Even if you're not particularly in the market to buy, the "surprise" value of seeing what's being auctioned provides a strong motivation to open the e-mail newsletterr each week.