Even if you aren't using XSLT on your sites, you've probably considered using RSS feeds to keep your visitors informed. The ability to quickly preview RSS and convert to HTML is one of the options you get with this XSL transformations plugin.
Need to convert blocks of text or HTML to htp.p() statements? This plugin makes it easier to create htp.p lines and convert them back to text / HTML. It also provides options for commenting / uncommenting lines and inserting related tags.
Virtually all major server-side scripting languages provide SQL-based functions for manipulating databases. The menus installed by this plugin can be used as a quick reference when they're not being used to insert SQL code snippets.