Alright, enough introductions lets get into it!
First off I'd like to say, if you aren't a picky audiophile and want a set of speakers that looks insanely awesome then this instructable is for you!
You are most likely wondering what exactly is a glass speaker? As randofo put it, "[T]his set of speakers resonates glass to produce sound. While this may seem complicated, the technical explanation is actually rather simple. Each speaker has a tactile transducer attached to the center, which is a device that vibrates the glass to produce sound waves."
You may be wondering how they sound and how well they work. Well the best way to describe it would be "glassy," if you ever get a listen you will understand. It has a very distinct sharp sound to it. The bass is surprisingly strong, and since the sound produced on a large surface (a lot larger than a regular speaker) you can actually feel and see it. One downside of these speakers is that the highs seem to get cut off and muffled slightly. To fix that I would suggest using thinner glass, although you'd run the risk of it shattering.
An additional interesting aspect of these speakers is that sound is produce on both sides of the speaker and it is not a one directional speaker. This seems to fill the entire room with sound better than conventional speakers.
Here is a video of the final result (keep in mind, the microphone on my phone doesn't do justice for the actual sound quality).
Anyways, enjoy the instructable!