Because so few people ever read all of the notes in a Steam changelog, here's a neat new feature a lot of people missed in a recent update: you can now opt to install multiple games at once.
So next time you binge during a sale, or just want to reinstall a bunch of old games from your library all at once, you can have at it. Note that while you're saving time on mouse-clicks, you're not saving installation time, as Steam just queues everything up (see below).
But whatever, that's Steam's business. For you, this is fire-and-forget game installation.