I use rd.io and would love the songs I txt in to be added to a playlist there. Or really a playlist anywhere - grooveshark, pandora, rdio, amazon, last.fm, etc. That'd be cool.
The only issue I see arising is that of internet radio laws. I believe (and I am no expert so please correct me if I am wrong) there is no way to 'freely' search for a song and have it be heard. Last.fm only allows previews (or radio stations that play similar songs) and rd.io is a paid app. I would love some way to do this for free. Yes Grooveshark does offer it for free, and I am not sure how legal their practices are.
Good point. My thought was to build a playlist over in a service I am already paying for. The songs I submit via TXT get added to a playlist on Rdio. Then, next time I login there - those songs are there for me to listen to. http://developer.rdio.com/