I discovered the Markdown bundle in TextMate, and what was cool was I could hit Ctrl-H to bring up a separate cheat sheet window for Markdown.

But, does anyone know if there’s a way to easily preview what I’ve written inside a browser?

Control-Option-Command-P will open TextMate’s own Preview as HTML window.

Ah! Thanks!

And now I see it’s actually right on the Bundles -> Markdown cascading menu… doh!