@arhuaco: I tend to forget about google docs; don't really use it that much.
@LinX: Hate you! I think ikiwiki does sanitizing, but I haven't enabled it. I guess.
Didn't know about slides using moinmoin. Interesting.
About Sphinx, hum, dunno. I kind of like it, but got somewhat scared when I saw the fuckton of files and folders it creates for any document. My ideal system is one that lets you do everything in a simple text format, but gives you a way of defining structure, and maps it properly to PDF and HTML documents. Sphinx kind of fits the bill, but is somewhat overwhelming.
@ceronman: oh God yes letters in LaTeX are awful to write. Yet, for personal use, I cheat and recycle any previous letter I can find.
The text, line-based diff system is enough for me, but I think one of the reasons for that is that I keep all my files at 80 characters per line. Have you tried that?
About slides, sometimes *Office is oh-so-handy. But you didn't hear it from me.
Para documentos sencillos, como una carta al ISP para pedir la cancelación de la cuenta de internet, uso Open Office. Para documentos más largos, como la tésis o wl CV uso LaTeX sin duda alguna.
A veces también uso un sistema de control de versiones, en mi caso Mercurial, pero no me parece tan práctico porque el sistema de diff basado en líneas y no en palabras no funciona con los documentos también como con el código fuente. Nunca me he puesto a buscar una alternativa para el problema de los diff, no sé si la haya.
Para notas utilizo Tomboy sincronizado a Ubuntu One para tener acceso a las notas desde otras partes.
Presentaciones con OpenOffice, todavía no he aprendido a usar el beamer.