Rush, Joe Bonamassa and Blues! to name three I've contributed to) and posting up-coming events (e.g. Rush's Snakes and Arrows Tour will let you see a successful past event and Joe Bonnamassa in Glasgow shows an event I posted). You can listen to streamed audio on the website or you can download the last.fm music player (Windows, Mac and iPhone versions are available) and recently it has started offering a few tracks as free downloads (e.g. Discipline by Nine Inch Nails). It also provides useful tools that you can embed in websites and blogs, such as the recently played tracks and favourite artists widgets at the right-hand edge of this blog and the player widget shown below.
A radio station based on the music I play.
However, the feature that really sold it to me is that the more last.fm knows about what you play, the better it gets at suggesting music you would like to listen too. For example, last.fm suggested I would like Dream Theater and Muse... and it was right! Oh... and you can link your music player (iTunes, Windows Media Player, Real Player...) to last.fm so that it can learn what you like to listen to more quickly.
Where do you get your music recommendations? What streaming music services do you listen to?