Excel. It's the single most useful application ever. You can organize and compartmentalize your data, statistics, plot lines, storyboards, etc etc etc. Plus it's full of math functions, drawing functions, flow charts, and it has VBA behind it. I use it for a lot, everything from organising types to working out the order I need to put game levels in, based on difficulty, lives taken, etc etc.
There is no other single package that can do all this, it can do practically everything you'd need. I even use it to make printouts for sketching character concepts - I take a basic human template, get it setup with information fields you need, statistics if you like - then print out loads, and you can just fill these sheets in and sketch out a character design. It provided the sort of toolset easily, that professionals would be proud of.
So, if you want to get organized with any project, get Excel. Ohh, and running it on a laptop instead of your work PC is just peachy - it's such an efficient way to work.