This plugin allows you add your own buttons to the post editor's toolbar.
*WordPress 2.9.1 compatible.
*Bug fix - Now you can use HTML entities.
*Bug fix - WordPress 2.8.4 bug fix.
*Bug fix - Now you can use quotation marks.
*Bug fix - Version 1.1 didn't really fix the bug, now it's fixed.
*Bug fix - Now you can add more then one button.