Mhm I just contribute to the Wikipedia... that one I feel is super worthwhile - it actually has been under heavy criticism by the US right lately, because they only want their version of "truth" to be the only one represented. Obv inconvenient for the powers that be, if there is freely available information that they can't control. I'm not contributing on any hot topic though (mainly music/bands) - but I still feel like everything that you can find on Wikipedia strengthens its position as a tool that people go to for info.

A local wiki also sounds cool, but I have no idea what I would contribute there.

Fully agree on the wiki editing. I think of it as provisioning the knowledge commons, i.e. knowledge commoning. Sharing good info is very important. IMO a community wiki (local or not, could be an online community) is just as good as editing Wikipedia. Even just posting what you know on your own blog/wiki/digital garden is valuable. One of the most visited pages on my personal site is my notes on how I fixed some crappy cat feeder, not going to foment a revolution but presumably it's helping people to fix theirs too and stopping some e-waste.