[Kevin Sevcik]

I'll toss in for "The Art of Electronics" by Winfield and Horowitz. While it seems rather massive, it's really helpful and focuses much more on an intuitive understanding of what going on as opposed to all the mathematical details. Admittedly, it's going to cover a LOT more than you'll ever need for FIRST, but then so does Machinery's Handbook. I'd at least look at it for a comprehensive reference like you'd use Machinery's Handbook for.