I have been calculating variations on scraps of paper.  A spreadsheet works much better.  Kind of looks like the big opening encyclopedias and you can be pretty sure if you have considered a variation in a hurry.  The cells are lined up nicely.  If you forget something you insert a row.  If your opponent remains within your worst nightmare (a variation you calculated that is strong for him) you can maybe cruise for a few moves without thinking quite so much.

Just a thought.