From Music Hack Day
An easily implementable system to add audio comments to any page similar to Disqus. Powered by SoundCloud.
Created by @marcohamersma.
 About the hack
Audio is so much richer than text, so why not allow people to speak up on any page? By adding a small snippet of code to page or a template engine, a list of comments relating to the post/page is loaded. You can authenticate with your SoundCloud account and record a comment which then gets posted to the user's SoundCloud profile. The track links back to the original post in the title, description and machine tags.
 Technology used
The comment form is loaded inside an iframe that links to the service with a the source url, title and optionally a color. When recording a new comment the source and title are added to the track by using machine tags. Originally I used SoundCloud's search API to find comments belonging to the url, but unfortunately the search index is not recent enough to do that that, so I used a local database storing the url, title, time and the SoundCloud track object in JSON. This gives me quick results but it also means that changes to the track and the user objects aren't reflected in the comments, neither are deletions.
The video of the demo can be watched here
Available on Github.