Comment year-month-event structure and then picasa (Score 1) 259
1) First, to avoid total chaos, make a strict year-month-event structure of all photos and use name of place if no event!...
2) Picasa is the ONLY program that automatically lists all photos without any import/export and database, and all tags you add in Picasa are stored on the photos, edits are stored too if you press the blue save icon, which copies the originals to a (hidden) subfolder.
Picasa also has a great face recognition engine, in preferences you must turn "save nametags to photo" for this to make sense!...
1b) Optionally, after sorting into event folders, you can do yourself a real favour by auto-renaming all your photos; I use Hazel for mac to give my photos the name 'event+month+date+year+time+iso+cameraname+filename' (from foldername and exif), then i can search for any event/place, know if it is likely to be noisy (high iso) and avoid duplicate finder programs or people accidentally deleting photos with the same name...
The renaming program should look into subfolders so all your files can be renamed at once, after setting it up and testing:)