Hey, great thread! I was looking for suggestions on this subject so I did a search on "organize" and found it. Lots of useful tips.
I've just updated to a Terabyte external hard drive, since my 250 GB hard drive is almost full!
I have three main subfolders under "Special" (code word for "Porn"): Pictures, Videos, and By_Name.
In the Pictures and Videos folders, I organized downloads by site: e.g. Twistys, Brazzers, KarupsPC, etc.
The By_Name folder has individual folders for individual models that I get the hots for. I then subdivide it into pics and videos. If I get a lot of vids, then I separate into Vids_Solo and Vids_Fucking.
Works for me.