Image Keywording

Does anyone know of any good programs that will let me add and search for keywords on my image files? I used to have a massive amount of pictures that were poorly organized with the Windows XP default file/folder system. Long story short, I no longer have any pictures, but would like to keep them organized better this time when I work up my collection.

>>2
Unless Danbooru has a download which will give me my own version of its tagging/browsing system, I'd rather not use it. I don't want other people tagging my shit; I'd like access to the system even when my or Danbooru's connection is acting up; and if Danbooru goes down for a long time again, I'd be SOL. Thanks, though.