What text to HTML converter for PHP would you recommend?
One of the examples would be Markdown, which is used here at SO. User just types some text into the text-box with some natural formatting: enters at the end of line, empty line at the end of paragraph, asterisk delimited bold text, etc. And this syntax is converted to HTML tags.
The simplicity is the main feature we are looking for, there does not need to be a lot of possibilities but those basic that are there should be very intuitive (automatic URL conversion to link, emoticons, paragraphs).
A big plus would be if there is WYSIWYG editor for it. Half-wysiwig just like here at SO would be even better.
Extra points would be if it would fit with Zend Framework well.