Plain text and other simple document types
Almost everything I deal with is plain text: Ruby, Lisp, Java code, detailed work log notes, design notes, etc. For information that I need to record just for myself, I get no benefit from styled text formatting. For other people I work with or want to communicate with, Latex does the job of generating great looking documents.
The Pier content management and Wiki system looks very interesting to me because it supports Latex output. That said, I am finding Google Docs to be a good alternative to Latex for very small documents. Anything to save time. Pier is open source and deployment using Squeak looks simple. (I have written here before about easy deployment of Squeak web applications.)