I've always liked library card catalogs - the old wooden ones with dozens of tiny drawers. Something about the grid or all the little nooks and crannies appealed to me. As a kid, my parents had a wooden filing cabinet, previously used to hold criminal records and fingerprint files, that they had bought at a police auction; it still had a number of old mugshots in it when we brought it home, and I guess the promise of hidden treasure is another reason I like these types of items.

If my house wasn't already crowded with furniture, I'd seriously think about picking up one (or more) of these:

• 15-drawer oak ($60) and two 10-drawer pine ($10 each) card files in Sacramento
• enormous 90-drawer wooden card catalog from Seattle's Ballard High School; bookshelves on back ($300) near Seattle
• pretty solid oak 60-drawer & pull-out shelf card file in New Jersey ($495)
• three-unit large-drawer library file cabinet in New Hampshire ($125)
• big beautiful 6-drawer oak card file in Minneapolis ($100)
• 1950s 60-drawer file in Atlanta ($300)
• 45-drawer cabinet with brass pulls in Raleigh ($225)
• huge 120-drawer cabinet with shelves in Phoenix ($400)

and here are a few on ebay

• little six-drawer card file in Scarsdale
• 60-drawer standing unit in Easton, Pennsylvania
• early 20th-century 24-drawer oak & ash cabinet in New Orleans
• big mid-century 60-drawer unit with shelves in Reynoldsburg, Ohio
• wide, 15-drawer tabletop unit in Kensington, Connecticut
• one of several 60-drawer units in Eugene, Oregon (see the others on the buyer's page; this style is also offered)
• 30-drawer unit in Hughesville, Pennsylvania

One thing I've noticed is that even the starting bids on Ebay are far higher than what folks selling via craigslist hope to get. Part of that is that Craigslisters want to sell to locals - they won't deal with shipping, and don't bother asking - and some of the Ebayers are willing to crate & ship. Another, something borne out by my own experience, is that people who use community sites like Craigslist are simply less predatory than vendors on Craigslist.