I use Excel and made a target that has 1" grid and at the bottom has all the pertinent data, I shoot and then put it into a three ring binder for reference.
You can get one at
http://www.ballistics-software.com
I make notes on the target for conditions, FPS, etc and it makes for a handy reference to keep from making the same mistakes.
Oh, and it helps a great deal to be able to see the actual groups for different loads