On Wikipedia, as far as I know, the normal way of communicating with someone is by leaving a comment on their 'Talk:' page. But I've never bothered to figure out the proper formatting conventions for talk pages.
But of course that information should be in Wikipedia, right? I was pointed to this page. However, the page describes three different ways of formatting comments, one of which is deprecated, none of which exactly match what's on Jacob Haller's talk page. (For instance there's a table of contents on the talk page.)
So as usual when I consider doing something on Wikipedia I find that it requires more motivation than I have to figure out how to do it. It's too bad that there aren't any existing simple ways of sending messages between people via the Internet that Wikipedia could have copied.