Tonight, I wrote down a bunch of fic ideas on little slips of paper and put them in a jar on my desk. I think it's a good representation of how the ideas get all jumbled up in my brain. I do also make lists of ideas on the computer, where I forget to open them later, or in notebooks, where I forget I've done it and then find them two years later when I've moved on to another fandom. My jar is right there where I can see it, so I'm not likely to miss it.
I like the physicality of it too, how each bit of paper is an idea, a unit. I feel like the actual ideas are in the jar, not just the reminder of where they are in my brain. I can reach in and pull one out and maybe I'll write that one or maybe I'll toss it back and try again.
And if I don't feel like writing, I can just admire the jar.
Do you have a special system to keep track of your ideas? Does it work?