Just came across this article and really enjoyed your list of resources, I will definitely check them out. Personally, I’ve been using hypemachine, reddit, and every once in a while The Kollection, which I don’t think was mentioned above. Just signed up for asongaday and can’t wait to get my first recommendations!
Similar to you, I love sharing music and hearing new songs, and I’d love to hear what you think about a music sharing tool I am developing (gettunedapp.com). Basically, it’s a way for people that (depending on the mode) share either a location or similar interest/music preference to share their favorite songs anonymously. From testing, this seems to give people more confidence to share more songs, including less popular songs that they might not have shared otherwise. Others within the same location or group could preview those suggestions and upvote them if they like it, creating a live, collaborative playlist that’s always changing. I think having an option available to locations would be super cool, so that you could always listen in to the local “flavor” of music around you, regardless of where you are. The app is in early development, and I’d love to have your input!