I love Faststone, and nothing else seems to touch it for speed and ease of use. It also uses very little system resources and you don't need massive amounts of computing power to run it. I'd love to see them add tagging, plus more than just one flag, and the ability to view and edit the exif information more fully. Hopefully one day it will happen.

I batch rename files as they come off my card, and shift them into the appropriate subject folders set up on my hard drives. I create file names which are basically tags. I choose up to about 6 words to describe the contents of the photos in a group, and then Faststone adds consecutive numbers to each batch of files I rename. If I can't find a particular batch of photos in my photos, Windows or Faststone quickly finds them from the file names. I've never bothered putting dates into the file names, because Faststone already knows that from the exif information and can sort according to dates if I need it.