Seagate 500 Gb Portable Hard Drive, $79.82 + Free Super Saver Shipping at Amazon
Staples comes in at a close second with their deal on this drive for $79.99, but most won't pay tax on the Amazon deal. If you do have a $25 off $75 coupon (or similar) for Staples, that would even be a better way to go. Here's the drive at Staples: Seagate link
Everywhere else has this drive for about $90-$100 or more.
Features:

• Plug and playno software to install
  
• Simply drag and drop to save files
  
• USB powered
  
• Built-in power management ensures energy-efficient operation
  
• 2-year limited warranty

(FatWallet Deal Hunter staff posts are certified ad-free. No money, bribes, or candy have been accepted.)