The Bowline
The Double Half Hitch
The Taut Line
I've thought about getting that knot book. I had to learn knots in Scouts and remember the ones I use: square knot, slipknot, Butcher's knot, tow half-hitches, etc. A reference guide would be nice, but I imagine its kind of hard to learn from a book.
I've found all kinds of uses for the Prusik, holds fast when it's under tension, but when it has slack, can slide. Never used it for climbing though