It's also a noveau term for web crawlers that visit web sites and "harvest" e-mail addresses for spamming purposes.

By the way, here's a little tip to help defeat these types of web crawler programs. If for example your email address on a web site is "justapicker@mudcat.org", you rename the address so that it is "justapicker@NOSPAM!mudcat.org" (of course with instructions to those wishing to send you email to delete the NOSPAM! portion before hitting send.) Messes up the spammers nicely and seriously cuts down on the amount of crap sent to you.