After scanning my Grandma Leola's collection of photos and memorabilia, I frequently found myself digging for similar photos. I see a photo of a farm and wonder if that was the same farm in another picture, but alas it is impossible to remember where that other picture is.
Then I realized that Google's Picasa photo program had a tagging feature, so I could be adding tags or keywords to all the photos as I went. Windows Explorer (at least with Windows Vista) also allows you to add tags to photos.
Now as I review pictures I have scanned, I tag them with words like kids, dogs, horses, farm, and cars. I also tag any photographer or location references that are on the pictures.
When all the pictures have the appropriate tags, it should be easier for myself and others to look through any photos of farms and identify if they are the same farm.