Update of "alternatives"
Alternatives to streamtuner2
RadioTray is a small systray/indicator application, which allows to quickly switch between stations. It comes with a few elected default radios, but easily allows adding new ones. Streamtuner2 now has a plugin to populate your RadioTray bookmarks.
Great Little Radio Player is a nice looking stream browser, which lists radios in a folder-style view.
TunaPie is a mature radio/stream player, which was popular among streamtuner1 users. It's still maintained, the recently released version is 2.1.19
VLC is not just a multimedia powerhouse, but also has a few plugins for radio directory discovery and browsing.
Rythmbox is meant for local multimedia collections, but comes with plugins for last.fm, libre.fm, radio lookups.