I use JSPWiki with Resin. I work for Caucho so I may show a Resin bias ;-).

I have a couple of things I use it for:

• building some free form website's for use by people who may not be very technically literate

• an attempt to organize the massive amounts of junk, ideas, correspondence in fax, email, and snail mail form, etc. that acummulate so rapidly on my computer