Dewalt's right-angle drill attachment is a nifty add-on for any drill (not just Dewalt ones) that allows you to drill holes and drive screws in confined spaces. It's a bit of a niche tool, but trust me, you'll be glad to have one in your kit when the time comes. As one Amazon reviewer puts it:

An extravagant tool, but when you need it, you need it.

In case you're wondering, any driver bits you use attach to this thing via a ring magnet rather than with a chuck. The attachment also has impact-rated gears that should last at least 2,000 life-cycles.

Get it for $23 on Amazon.