a good cable cutter is a great thing to have for cutting power/ground witre. they are like $18 at home depot
a set of sockets and ratchets as well as screwdrivers are great to have
bernzomatic propane torches are handy for soldering large cable.
bent coat hangers and or flexible items for snaking cable make things much easier. i've used everything from screwdrivers to zip ties to pipe snakes to run cable through tight spaces
if you are working on a GM car, Star-bits or star-drivers are necessary for all the star bolts in the dash. I think my car they were mostly T15 size, but T10, T20, and T25 were also used
don't have pics of my tools, but