I’ve been using Post Haste since I read a tip from EditingWhiz about keeping your video files organized so you can find what you’re looking for. It’s a free program from Digital Rebellion that has templates which automatically set up folders for different media from FCP, After Effects, Photoshop, etc., and creates a dummy file in each folder with a consistent naming convention based on customer name and date for that project. It’s customizable for your own situation. I’m on a Mac but I think they have a Windows version too. Coupled with a disk cataloging system like DiskTracker, you can find files easily across multiple internal and external drives.
I’m using a Newer Technologies Voyager quad interface external drive dock and about a dozen (and growing) 1 to 3tb drives that I use to archive projects. The Voyager has Firewire 800 & eSATA which speeds up write times a lot over USB.