I don't understand the include everything mindset, and I think I'm in the inclusionist camp. If you encourage other people to put data on Wikipedia, the value of the data drops to zero from an economic and reputation exploitation standpoint. For example, if you think there is value in having a comprehensive list of hacker spaces, set up a site that lists them and maintain it. You'll be known as the person who maintai…
In particular, Wikipedia's an encyclopedia; that means it's a tertiary source, which means everything it includes should ideally be cited to secondary sources (books, journal articles, newspaper reports, etc.). There's lots of interesting information you could document that doesn't work in that tertiary-source manner, because the secondary sources don't yet exist. So a project to do original research/compilation/etc. in an area where its contributors are knowledgeable is great. Know Your Meme is actually a pretty good example of that. A hackerspace directory would also be useful. Something like http://www.killfromtheheart.com/, also great.