I just got one, and although it's not as good as advertised (claims to make 2 speakers into 5.1 speakers) it is still very good. If you are using your TV's built-in speakers, a simple stereo amp or computer stereo speakers for your entertainment center I'd highly recommend it.
I even tried it with my dad's surround sound system with stereo input from satellite and it works OK, tho it did do some weird low level buzzing noises during some commercials which already had spatial surround processing on them.
What it does is take line-level audio and apply SRS Labs most popular DSP programs to enhance the audio.
The remote lets you control which enhancements, and how much Trubass boost is applied.
The false 3D TruSurround isn't incredible, but I find that it does make the audio seem to fill the room better without needing to turn the volume up. Likewise, the TruBass doesn't make small speakers produce sub-bass rumbles, but instead enhances the frequencies that standard stereo speakers can produce and introduces harmonics to simulate those lower frequencies. It's the most substantial enhancement that this unit produces, it has 7 levels of bass enhancement.
Finally, the Clarity function makes vocal frequencies more pronounced and makes dialog much easier to hear when there are many other sounds in an audio track. All in all it makes the audio sound much better.
These units used to sell for $100 or more, but they didn't sell well, my guess is nobody knew they existed. Now, since there were so many produced and liquidated they can be purchased for $25 or less.
You can get the same effects with more control for Laptops (Toshiba Virtual Sound, SRS Audio Sandbox) and ipods (SRS iWOW). Many MP3 Players and TVs have some of the functionality in them too. What sets this apart is it will work with whatever hardware you have.
Review
Edit: I think this site is influential - they just got expensive (mine was $21 shipped). Ebay's not a good source anymore so look elsewhere. Don't spend more than $25... Try Amazon or google.
