I've got five cameras out now, and had six all summer. Most of them have been out since March. I give each set up a name. The cameras that are in the same general area, I use the same name then a #1, #2, #3, etc.
I then have an Excel spreadsheet to keep track of each camera and the dates I checked it and the dates that I changed batteries.
Every time I check a camera I replace the memory card with a clean memory card. Then when I get home I copy all the pictures into a folder with the name of that set up followed by the date (mm-dd-year).
For names just use road names, creeks, landowner names, just whatever key word will remind you of the location of that camera.