And now for some specific tools/resources related to my instrument (guitar) that have made the most impact...

- A good guitar
Not necessarily expensive, but one that feels good to play (that first one I had played like barbed wire on a telephone pole) and sounds good to me. That also means the right string gauge and setup. Makes a difference. These days a good guitar doesn't have to be expensive.

- An electric and an acoustic
Both. Its all about options. I play them differently... don't know why, just do. The electric gives me a wider sound palette. The acoustic is just me and the guitar; plain and simple... it is what it is. For electric, solid body or semi-hollow or hollow makes a difference. For some things I use a solid body, for others a hollow. Same with acoustic, different materials, different body sizes. There's always a difference from one guitar to another, sometimes slight, but options are good. I discovered that any electric plus any acoustic is the most useful base for me.

- A good modelling amp
Played through a JC-120 for decades. Never thought of anything else until recently I picked up a Boss Katana. Opens a huge sonic palette and that's really useful and interesting. Its pushed me in new directions.

- Band in a Box
I find it to be quite valuable. I use it to set up backing tracks in various styles. These I use to maintain and improve my improvisational skills. Its tough to improvise to silence.

- The Public Library
They have a huge collection of CDs. I can check out and listen to any kind of music for free. They also have a decent collection of printed music. Great resource.

- Every guitar player I've ever heard and quite a few horn players too.
I think I've learned at least a little something from everyone. I can't think of any particular guitar player I admire most, but the most influential for me during my formative years were Charlie Christian, Wes Montgomery, Doc Watson, Bert Jansch, Merle Travis, BB King and Leo Kottke.

- One night in February 1964
The Ed Sullivan TV show. Those four guys from Liverpool looked like they were having so much fun that I thought "I gotta do THAT. Right now right away."