PageSpinner is a Mac app for writing html with live previews. It's apparently been around quite a while, and I'm somewhat surprised this is the first I've heard of it. Apparently missing robust search & replace functions (like jEdit, BBEdit, or Ultra-Edit have), but might be worth checking out next time I'm near my Mac. Not that I get to do much html any more at work; it's all VB.NET, ADO.NET, Oracle & Windows.Forms right now.