What are the best methods for using online music services for new music discovery?

TuneIn by Google Play. You can find this app here: https://play.google.com/store/apps/details?id=tunein.player&hl=en This is the best music app, I have ever found. It gives you the live feed of most of the international rock stations. Best thing about radio is that they will play only that music which was/is popular. So whenever I picked any radio station and just listen to the live music feed, its awesome. Coming to your problem of discovering new music, this app provides you with list of radio stations with current song being streamed and you can chose among musical genres, artists and even your favorite bands to discover their other songs.

Many digital distribution sites such as http://www.beatport.com/ and http://www.djdownload.com/ have genre tabs which make it possible to refine your search to quite a large degree, they also feature a 'people who bought this item also bought' section and 'recommended for you' based on your previous purchases. (Incredibly handy if you are a DJ as they don't seem to have much in the way of quality control.) Itunes has 'Genius' which has many amazing features. http://ipod.about.com/od/itunes/g/itunes_genius.htm https://soundcloud.com/explore is another favourite of mine. It features a waveform of each track with a bar running along the bottom where you can post comments. You can 'follow' people and see what music they have listened to, listen to music they have created and browse through any groups they are in. as well as its broad folksonomy tagging system http://www.vanderwal.net/random/entrysel.php?blog=1635 and immense amount of free downloadable music. It has become the defacto standard for unsigned and signed artists to promote themselves and their music.