Look up the word at the cursor in Google, Open Directory, Acronym Finder and other similar resources on the Internet using the right click menu provided by this plugin.
If you're editing text and HTML documents that have extra spaces at the end of lines, the process of trimming such lines can take some time. This plugin can help by automating the removal of end-of-line whitespace.
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.