Music and the web aren't exactly a match made in heaven. There is the often unfortunate use of bad music as an annoying background feature of website as well as the simple fact that the quality of sound, particularly streaming, still isn't great. On top of all that most laptops and computers don't provide for very good listening experiences.
Even the creative uses of sound and music have been rather lackluster affairs. Music mixers that turn loops on and off, even when they're fun aren't fun for very long.
There is a phenomenal recently released exception: Hobnox's Audio Tool. A brower-based music production application that features all the classic electronic music gear, the TB-303, 606 and 909 drum machines as well as an assortment of effects. It sounds great, it looks great and its easy and fun to use (esp if your familiar with the analog versions of the gear).
Someone's even hooked it up to an oversized touch display. Dope.
Propellerheads software's failure to rerelease ReBirth for Mac OSX was really painful for me. I had, literally, hundreds of songs and audiofiles I created using that software that are now inaccessible to me. I would love it if someone figured out a way to open Rebirth files and load them into Autio Tool.
The ReBirth Museum