I joined wikipedia to rewrite sentences with awkward "however" clauses tacked on. So far, I have spent more time doing other things.
I found another thing I like to take care of: editing pages so sections contain discrete information. For example, when an introduction has 5 paragraphs of history on a computing topic and tons of implementation details or usage examples, I like to cut them out and put them under their own subheadings. Information needs to be organized to be useful!