"Speaking" - being able to express any of your thoughts with sufficiently many words while applying the language's grammar correctly.

I don't know how to create polls with the possibility to select >1 answer, so it's a bounty instead (which is also possibly more fun);

Instead of voting, write the name of the language in BOLD CAPS (if you're the first one to mention it) and write a > 10-word original text in it with a translation provided, so that others can check if it's correct. After confirmation of grammatical correctness and sufficient meaning (repeating one word 11 times doesn't count), most likely by me, I will award a 100-700 mana bounty, depending on the text's impressiveness (inherently lower for Toki Pona, etc.).

If someone has mentioned a language you speak, you won't necessarily get a lower bounty (if you don't copy their text, that is), just write your message as a reply to the first mention of your language.

I got introduced to EA/rationality at an Esperantist event, so there is at least a minor overlap in that regard and with the creation of Mini, maybe there will come a resurgence of other conlangs (Lojban has/had some fans on LessWrong for example).