Wii2600 is an Atari 2600 emulator based upon Stella.

Stella is a multi-platform Atari 2600 VCS emulator released under the GNU General Public License (GPL). Stella was originally developed for Linux by Bradford W. Mott, however, since its original release several people have joined the development team to port Stella to other operating systems such as AcornOS, AmigaOS, DOS, FreeBSD, IRIX, Linux, OS/2, MacOS, Unix, and Windows.

Notes for the initial release:

Initial release
Wiimote/Classic/GameCube controller support
Mouse via Wiimote for paddle games (proof of concept)
USB Keyboard
Audio/Video etc.
Save/load state
Screenshot support