If you haven't already, download the FREE photo editing software from Google - Picasa
In addition to all the usual photo editing stuff - crop, straighten, red eye, add light, add shadows, make collages, there is this very neat feature:
Add name tags -- Picasa scans all the photos in your collection, identifies the ones with faces, and groups photos with similar faces together. It's easy to add name tags to dozens of photos at once by clicking "Add a name" below a photo and typing the person's name. Once you've tagged some pictures, you can make a face collage with one click, easily find all your pictures with the same two people in them, or upload your name tags to Picasa Web Albums.
The first time you open Picasa, it will scan your photos for new faces. It can take some time to scan all your photos, however you can start adding name tags whenever you'd like. Each face thumbnail in the album represents a group of similar faces, so adding a name to a face thumbnail applies the same name to all the faces in the group.
It does take a long time for the initial scan, but you can just let it run in the background while doing other stuff on your computer or just leave it to run by itself.
Initially you will end up with a hodgepodge of head shots (mug shots?) like the ones above, but once you start adding names to them, they will separate into folders of all the same person in each folder.
This will spark questions like - who is that person? Who are all these people? When did I take that picture? - and you can just click on the head shot and it takes you to the bigger picture that the face came from.
Then you can do what you want with them, including making collages like the ones I did for Carrie and Melissa.
Lots of fun, more stuff to distract you while you are supposed to be working… ahh modern technology!