From their site: What is tunelog?
Think of tunelog as your music data repository. Not storage for your music itself, but for all the data about your music. What you own, what you play, how you rate everything, how you tag everything...your reviews, your watch lists, your stats, your data. What your friends are playing. What your friends are saying about their music. Use tunelog to consolidate your music data as you play from home, play from work, play on the go. People are writing tools to automatically pump all your stats into tunelog so you can do cool things with it.
The following is a list of historical changes that were made to this asset. Typically,
once an API is published on ProgrammableWeb.com, the data we keep about that asset gets updated over the course of its life. For example, the endpoint or home page of the documentation might change.
As a means of enforcing the integrity of our data, every time a non-trivial change is made to the data we keep about an asset,
we require the entry of some changelog text before that change can be saved. This way, we have a great audit trail of all
activity surrounding the asset. For each asset, the changelogs begins with the moment an asset is approved for publication on ProgrammableWeb.
If you spot an error in our data and believe that a record needs to be updated in some way,
the ProgrammableWeb team would very much like to hear from you at firstname.lastname@example.org