we do some parties over the year (birthdays, new year, summer, etc.).
Our guests have different music preferences (from heavy metal to psytrance).
Therefor it's really difficult to compile a playlist that everybody likes.
Now I had the idea to provide a link with the next invitation where our guests can compile their own playlists.
Basically it should be a simple web form where they can enter a title and add it to the playlist.
It sounds like you should use the webapi to communicate with Helium:
It should offer you enough methods to search and add to playlists.