SRS Labs' iWow 3D is a dongle (dongle? dongle!) that plugs into the 30-pin connector of your iPhone, iPad or iPod to make it sound more awesome. Does it? Well, gamers, listen up.
Plusses:EQ adjustments in iOS only affect songs played in the iPod app, so the iWow proves its mettle when it comes to movies and games. Because the iWow runs through the 30-pin connector, it uses unsullied audio from the onboard processor. While whether or not the sound is "3D" depends on your definition of 3D, the audio is definitely enhanced, especially when it comes to bringing background sound effects to life. Rumbles have more texture, crashes have more pop, and smaller, sharper sound effects like snaps, cracks and plinks sound more lifelike. Audio-heavy games like Sword and Sworcery, really pop with the iWow.
Minuses: Music. Any audiophile would recoil in horror if they used the iWow while listening to music. I tested the iWow with the provided headphones, as well as my own pair of AiAiAi TMA-1s, and the result was the same. Vocal quality is diminished, taking on a treble-y an almost translucent quality. Instruments and sounds that have been intentionally mixed down into the background are brought back up, completely changing the song (and not for the better). Don't let iWow near your music.
It's $80. [SRS iWow 3D]