Mind Map Update
I had initially started making my mind map with Mindomo, thinking that it was completely opensource software (my mistake). I hit a wall discovering it was 'freemium' software - it's free within certain boundaries, and it prompts you to purchase a subscription if you want to create more than 40 nodes.
So, after a bit of searching, I found Freeplane - which is well and truly a completely free, opensource mind-mapping tool. It did require a bit more learning and you do have to do everything manually - all the way down to choosing the colours of your links (no templates here), but once you get the hang of it, it's a fantastic tool that allows you to have a lot of creative freedom (for something that costs you nothing, that is).
So, Mind Map update - it is still pretty incomplete, but as a tool, it definitely works for me.