This deal has ended.
Buy.com has the Kensington ComboSaver Combination Notebook Computer Lock on sale for just $18.71 after this $10 mail-in rebate (through 6/8). This features a six-foot steel cable to anchor your notebook to anything and a T-bar locks into the Kensington security slot found in 99% of all laptops. There's also online registration for your combination so you'll never lose it. Shipping is free, there's no sales tax, and new Google Checkout users can get an additional $10 discount.