Google's Picasa is the single best free program for photo management, editing and sharing.
It has just about every function you can imagine. If you want a comprehensive photo application, this is the one to grab - it can manage your photos, display on Google Maps where they were taken, perform sophisticated editing tasks, and help you share your photos.
At its most basic level, Picasa is a photo manager and viewer.
Run the program and then scroll through your folders, and you'll see thumbnails of all your images.
You can also tell it to show photos only in a certain date range. If you want to see just photos of faces, choose the Faces filter toward the top of the screen, and Picasa will try to find only that type of photo in the folder; the feature doesn't always work properly, and it will likely bring up a few pictures without faces, but it's a good first cut.
Viewing photos is only the beginning. You'll also find solid editing tools for cropping, eliminating red-eye, changing the contrast, retouching, and more.
The tools are exceedingly easy to use - far easier than the functions in competing programs. Picasa even has an 'I'm feeling lucky' button that performs cleanup automatically.
In addition, Picasa lets you create CDs full of photos, as well as photo collages, screensavers, and posters.
It can upload your files to Google's web albums photo site, or publish your photos to your Blogger blog.
It also can geotag photos, adding information to them for identifying where they were taken; afterward it can display on Google Maps where those geotagged photos were captured, and show such information right inside the program.
Picasa does have a few faults. First, it can take quite some time to scan your system for photos, so be prepared to wait until it finishes.
Fortunately, it scans in the background, so you can get on with other work in the meantime. (Even so, unlike many other photo tools, upon launch it doesn't let you immediately work on your photos.)
Second, the interface can be daunting and confusing, so you should expect to do a bit of learning. Once you put in the time, however, you'll find the program to be a spectacular photo editor and manager.
Note that when you install Picasa, it tries to make Google your default search engine. If you don't want it to do that, uncheck the box next to that option.
Also during installation, Picasa will set your system to send anonymous information about your surfing habits to Google; uncheck the appropriate box if you don't want that to happen, either.