Quick-tap Option for Adding Songs to an Existing Playlist

When a song is playing from an apple device (ie. Ipod touch/iPad/iTunes), there SHOULD be a quick tap option to add the featured song to an existing playlist.

Sometimes, when someone plays a song and they realise it's good for a particular existing, it gets rather annoying having to go the playlist, press the '+' option and then scroll through hundreds of selected songs just to find the one that was already playing... don't you think?

Please consider this option, and make it possible for future Apple users to make infinite playlists possible.