So Terez asked me to find and/or make her a HTML editor because she doesn't want to write all her tags herself. I found a few, but none of them were particularly awesome, so I made her one.
here or here
I'll quite happily add you more buttons if you want. The main feature was the Alt-to-view thing, the rest is just powered by jQuery and a bunch of code that adds selection functions to jQuery I found on StackOverflow. I might add some way of centering the preview on the cursor, if that becomes a problem, and I don't know how well it works over browsers.
unfortunately its also not clever enough to allow you to undo anything, which is a major sticking point, I think... Silly jQuery
Go ahead and ask me to improve it