An ongoing and non-exhaustive list of various music and art tools that I use. Most are free. Will update whenever I think of it:

• REAPER
  Best DAW, used for everything, completely customiseable, runs on a toaster, tons of stock VSTs and JS effects that are beyond useful. Tons and tons of resources, videos, instructions, all easily found online. Can be used for editing video too.
• MT Power Drumkit 2
  Free but donate anyway to get the version with no start screen. Simple to use, great sounds, just works. Couldn't recommend it enough, I use it on everything.
• Dragonfly Reverb
  A nice selection of reverbs, I find the room reverbs particularly useful.
• IGNITE Emissary and NadIR
  Guitar and Cabinet emulation. I don't use these on finished Guitar recordings (I just mic an actual amp) but they are ideal for writing at home and sound great. You can get some very useable sounds out of the Amp, and the cab sim comes with decent IRs. There's other software on there I have never used and I don't know if it is free or not but these two are.
• TSE Audio BOD
  It's a SansAmp Bass Driver clone. If you're recording Bass at home, it is great. Again it hasn't ended up on NÍLIM (no bass) but has been used on tons of other recordings I've done in the past few years.
• VLC Media Player
  I would be genuinely shocked if this wasn't already installed on your computer and you are reading this.
• GIMP
  Couldn't ask for a better image editor. Can have a bit of a learning curve but again once you find your workflow in it, it is excellent. No end to the resources and tutorials online. Used for almost all art & image editing I do digitally.