Torches and pipe cutters are pretty standard.
Right now I've got a great
de-burring tool I'm in love with, ten times faster than sandpaper:
...It's so important to have clean copper before you solder.
How about
plumber's tape? Bend it back and forth on itself to break to length, screw or nail into joists and beams to tie up plumbing where it's not supported otherwise:
...Also great for the motorbike enthusiast. :D
But the single greatest tool for DIY
anything: a
sawzall. Specifically, a Milwaukee one:
...I used to have an old one that weighed about 7,000 pounds, I think it was made out of pig iron. :D The new ones are plastic, and boy is that great. Get the right blades and cut through anything, no matter how hard it is to get to. I used one just yesterday to cut a length of 2x4 down to 1-1/4 inches wide, to replace a piece of door stop in a closet. With a little practice it's almost as good as a jigsaw on plywood and sheetrock, and can get through pesky 3-inch copper pipe in odd places like it's made of butter.