Over the years I find that certain things continue to please and indeed often seem better today than on my first encounter. I thought I’d collect a list of such things as recommendations. Some categories will be separate pages; categories with a smaller population are collected here.
Kettlebells — a great workout that somehow still manages to be fun, perhaps because you can segue from exercise to exercise without stopping. My post and a recommended site (thanks, Joel)—explore the various sections for more info.
Horn combs — they are truly great.
Esperanto is a language specifically constructed as a (politically neutral) interlanguage: a common second language that people can readily learn (no irregular verbs, for example, and an easy way to extend the vocabulary). Moreover, it is (a) fun and (b) is an ideal first foreign language to acquire, making subsequent foreign languages much easer to learn.