I tend to be more of a user and less of a contributor with regard to wikis. It's probably a combination of laziness and self-consciousness.
Someone recently posted favorite eating spots to QL Chat. I've often dreamed of a staff wiki where each community library and central have a page that lists information about the area, including food and transportation.
When looking for employment last year, I used the "Looking for a Job" page of the Library Success wiki. I also like using wikis to search for booklists, like the ones on TeenLibWiki.
A week or so ago I modified the formatting of a booklist on the YALSA wiki, only to have it later modified by another user. Potato, potato. This is probably why I don't tend to contribute to wikis.
*This is paltry entry. I'll probably add more later.