tpi.wikipedia.org - Tok Pisin One of the official languages of Papua New Guinea. Some pages should be moved from temporary work at bi.wikipedia.org over here.
io.wikipedia.org - Ido Ido is a cousin of Esperanto, rarely seen but of some historical interest.
tp.wikipedia.org - Toki Pona Toki Pona is a more recent conlang, but with a relatively active and enthusiastic user base. ('tp' is not assigned as a 2-letter code, and ISO isn't assigning any more 2-letter codes. Rather than fight about what to call it, I figured 'tp' will do.)
-- brion vibber (brion @ pobox.com)