3 It'd be nice to be allowed to insert tabs into the textarea, as opposed to having to insert 4-spaces for lists/etc. This would require JavaScript to be practical, and would gracefully degrade on browsers w/o JS support.
5 Some browsers already let you insert tabs (IIRR links or lynx does...)
7 Here's a link to a wiki discussing the topic: <http://c2.com/cgi/wiki?TipForTypingTab>