I've been telling myself this year I'm definately going to start that log and every year I just keep updating the mental one. Sooner or later however, my mental one ain't going to function as it should and my warranty is long since up

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For those that have excel, it makes a great place to keep records and for a couple of reasons. You can sort by a location, you can sort by a date, or even sort by weather patterns, as long as you are consistant about the way you log the entries. Another nice feature is you can keep it simple, yet create hyperlinks to articles or more detailed notes on your hard drive. I've even got some tips on this on my webpage.
There are some commercially available logs, but excel or lotus will basically do it all for you.