As per my request, I've received quite a few recommendations for polling packages and have settled on Democracy AJAX Poll (thanks Hale), which is exactly what I was looking for, not to mention the fact that it's already packaged as a WordPress plugin. It has everything I wanted and was reluctant to mention in the previous post: simple IP-based cookie system for blocking multiples votes from the same person, CSS bar graphs (no images), ability to link to specific polls (because I'd like to run them as regular posts),1 and it's written in PHP. Perfect.
I'm not quite sure what I'm going to be polling about (past the first one that I'll likely put up later today or tomorrow), but I do think they're 'fun' and will try to get them up here somewhat regularly.
As ever, I've thought a lot about the polls' "future-proofness" and when the time comes that the plugin is no longer maintained (and I myself can't find the time to keep it going), I can simply go to each post that contains a poll, copy the generated source, paste it into the post itself, and then note that the poll has been closed. In other words, I'll never lose the results. ↩