I do something similar.

Make a year folder "2008" then every time you upload a card you upload it to another folder within the year folder and reverse date it and put a keyword which will remind you what "day out" or scenario you were shooting in: "2008_01_23 - Bill's Wedding" or "2008_07_11 - Walkabout with Dave"

Then when you look back you will remember that on your walkabout with dave (in the summer) was the time you took that nice shot of a field of Poppy's or something.  That way you will not have to "sort" the images at the end of the year, or at least it will make it easier to find that particular picture you were looking for.

ETA - the reverse dating is so that when you click on "arrange icons by > Name" they all arrange into chronological order.

I would warn against using the "themed" approach, i tried and i just kept on mislaying images.  The other thing to do is to keyword your shots - i dont do this, but others do and find it effective at locating shots long after the event.

"In every colour, there's the light.
In every stone sleeps a crystal.
Remember the Shaman, when he used to say:
Man is the dream of the Dolphin"

Rich Meadows Photography