I actually got a notebook designed for that for Christmas. The book that I got has spaces for the following:
Target, City, Date, Day, Time, Weather/Temperature, Fishing From (shore, dock, boat, ice), Location, GPS, Area Fishing Reports, Fishing With, Fish Bait/Lure/Fly used, First Fish Caught By, Biggest Fish Caught By, Most Fish Caught By, Total Catch of the Day, Comments, Special Tackle Used, Highlights of the Day, Places to Remember for Next Time, and then a blank page for notes.
Some of them seem more beneficial than others, but I think that it is a good idea. Unfortunetely I have not yet had a chance to fill out a page yet.