XML format and XSL converters to generate HTML, PDF, and RTF resumes (that last one was for recruiters, so they can remove your contact info and add buzzwords).

For a while, I maintained my resume in XML and ran it through XSL/FOP/JFOR to create various presentations (and contributed a kludge for proportional columns in JFOR).

Now I'm using a semi-standard JSON format that has better-looking themes, but one thing that I liked about this one is the grouping by industry.