"When will I ever need these?" I would mutter...
Fast forward twelve years and here I am, going back through my 50,000-photo Lightroom collection, adding keywords.
Even if--especially if--your photos consist of nothing more than family and friends, you should come up with a small set of keywords. That set should contain peoples' names. Simple, right? I know iPhoto and Picasa have the "faces" feature, and that's really cool. But it's a good idea to get in the habit of adding the keywords yourself.
All of the major photo library software options that I know of support keywords in one way or another. Since I use Lightroom, I'll give you the primary reason why I am now adamant on using keywords.
I started adding keywords to my photos a few years ago, so a good portion of my photos contain metadata that lets me utilize the smart collections. I have one collection for each member of my family, and any time I tag a photo with one of their names, it automatically shows up in the proper smart collection. So if I'm looking for a photo of my daughter from 3 years ago, I don't have to hunt through endless folders to find it. I just hit up her smart collection and scroll through till I find the one I'm looking for. Even if you don't have Lightroom, and your software doesn't support smart albums/folders/collections/whatever, adding keywords to your photos will make it easy to search for a photo.
As an added bonus, if your software saves metadata to files, those keywords will remain with the photo no matter where it goes. And if you're working in Lightroom, keywords will become tags when you upload to Flickr.
So there you go--no need to get fancy if you don't want to. Just add names as keywords. Five years from now, you'll be glad you did.