Eddy Elfenbein submits: I often hear people say that a particular stock is so cheap, "how much lower can it really go?" The answer is, it can go a lot lower.
A stock can drop 99% and it's still not at zero. It can drop another 99%, and it's still worth something. In fact, a stock can drop 99% many, many times, and still not reach zero.
Delistings don't make a lot of news, but they happen every week. Here's a graph of issuers on the NASDAQ since 2003: