Amazon.com is offering a NES or SNES USB controller for a good price.

NES USB Controller for $11.71
- Purchase a total of $25 worth of goods to get free shipping
- Works on Windows
- For emulator, Jnes is a good NES emulator for PC

SNES USB Controller for $10.12
- Purchase a total of $25 worth of goods to get free shipping
- Works on Windows and Mac
- For emulator, ZSnes is good for Windows and SNES9x for Mac