I have an app on my Droid that marks this type of stuff down when you catch a fish, so that you can go back and analyze the conditions.
It tracks the location and you input the fish, location or lake name, weight, length, bait type and bait, and the weather conditions as well as the moon phase. You even take a photo of the catch for logging purposes. That app was free IIRC. I know there was a paid app that did stuff like Jason described.