Girlfriends (Or temporary rentable substitutes)
Big 3 upgrade that's not electrical (Intake, headers, exhaust)
Car skills that aren't audio related (OMG OMG OMG, It's grease, yuck! What do I do?!?)
Porn free hard drives (93% of the internet is porn, or was it 97%?)
Opera or Firefox web browsers (Tabbed browsing makes 93/97% of the internet FUN!)
LINUX (93/97% of web sites have bad things targeting Windows PCs!)
A healthy amount of ingenuity (I have plexiglass, MDF, tin, plywood, flat PVC, and random sheets of blue plastic around the house! But I have to buy a new component set because these 5.25s won't mount in my 6.5 spots!
Common sense (I see smoke and smell something burning coming out of my amp, and it's glowing cherry red in 2 spots, did I hurt it? The answer is always YES.)
The list goes on and on.