Here is the solution: Organic Traffic. I am not technical so excuse it if I sound naive. Ajax is beautiful, but if you have a content site and want traffic, you are going to hurt your search engine results, and that counts because sooner or later that should be your main traffic source. You need to turn those categories into more pages meaning whenever someone plays a song or creates a list, that becomes a page with a neat URL that the search engine can actually spyde. Think about it, if someone searches on Google for one of the songs you have in your DB your page can actually show up on the first page. Start indexing those playlists/channels/users pages and you will double your traffic.