phranque - 7:48 am on Mar 11, 2013 (gmt 0)

I'm pretty sure these links aren't from my sites

you should crawl your site with a link checker rather than guessing or assuming.

Do you think it's worth the effort to redirect (301) these URLs to a newer article?

only if the "newer article" is a replacement for the content at the previous url or is at least highly relevant.
otherwise, you should provide a 410 (Gone) status code for the response, assuming that the url actually existed previously.