I kept a fishing log (mainly bass) for 5-6 years in an Excel sheet. It was pretty awesome being able to sort/select the info you wanted. It really came in handy for tournaments/league events. Below are the categories I filled in after each outing.....
-Lake
-Date
-County/Area
-Species
-Air Temp
-Water Temp
-Barometer
-Water Clarity
-Time of Day
-Wind & Direction
-Current Weather Trend
-Weather
-Bait
-Depth
-People Fished With
-Hours Fished
-Best Producing Lure & Color
-Results/Comments
-Biggest Fish & Lure
-# of Bass over 18"
I would highly suggest doing this if you have the time! It can come in handy if the wife says your fishing too much and you have the data to show her you have fished X amount of times/hours less than last year. Or put it into a pie chart showing how much time you spend with her vs. fishing. :D After having a couple of children I have not kept up on it due to lack of time and not fishing as much. I do go back and read through it occasionaly...some great trips and memories that I will always have! Hopefully it will be of some use to my children and grand kids.
Bassman