As a new user to Markdown I was looking for a cheatseet. For some reason the meaning of cheatsheet has become diluted to mean a bunch of scrolling text that would print out to multiple pages with inconvenient breaks; the first 5 suggestions from Google were such. Fortunately Jeremy Stretch has produced a sane pdf cheatsheet that can be viewed or printed out as a convenient single page desktop reference.
Jeremy’s blog PacketLife.net has a whole stack of well formatted IT cheat sheets, mostly networking related, but worth a browse including a single page Mediawiki cheatsheet.