logging software, no "b"

I like to track a bunch of things about my life for future reference. Sometimes irregular diary entries or notes; more often, regular things like when I got to work or what I had for lunch or dinner or what T car I rode on (I gave up on that one after I had collected the entire set of Red Line cars and was no longer riding the Green Line daily). Most of these end up as text files, or occasionally palmpilot memos, with date-stamped and sometimes time-stamped entries. I've got enough of these floating around that it's starting to seem like I should consolidate them. I think what I want is a little database with timestamps, tags ("food,lunch", "food,dinner", "work,arrival", "diary"), and free-form text.

This sounds a bit like blogging software (entries, tags, etc), except I don't particularly want to publish this or have someone else host it, and many of the entries are going to be quite short.

Any suggestions for software or tools to use for this? Plain text is always an option, though keeping the formatting sensible so that it's easy to extract by tag later is a pain.