Build a brouser based audio track recorder

I would like to create a brouser based audio track recorder. The customer would need to be logged in to use it and the audio files are stored on their computer. This could be a brouser add-on or Javascripts or flash or a separate program that will need to access the internet for vital files. I want to own this software 100%. I want it to be completely expandable in the future, by yourself and other programmers. I would prefer someone who is experienced in programming for audio multitrack recording software. The use of open source software will be fine as long as it is expandable in every way and you add all the features I require in the first version. These features will be negotiated before commencement and acceptance of your bid.