Ask HN: What desktop applications would you most like to see “Firefoxed”?

Firefox (originally named Phoenix, then Firebird) was, in 2002, a reaction against the Netscape Suite™'s kitchen-sink approach of piling on features in order to tick marketing checkboxes, and an increasingly complex user interface that wasn't serving users very well.

What desktop software do you wish would (or could) be reborn today as a leaner, simpler alternative?