If you use iTunes (and if you're reading this, I know you do) and Last FM, you'll find life easier with Everyplay from Snarb.tk (http://snarb.co.uk/everplay.html). The US$19.95 app plays music from your iTunes music library, as well as from Last FM online radio services (last.fm).
You can browse, search and play your iTunes music library and playlists in one Cover Flow window without launching iTunes. This is a screen real estate saver, which is important if you're working with a small screen -- says, on a MacBook or 13-inch MacBook Pro. What's more, play count and other iTunes metadata is automatically updated as soon as iTunes is launched by Everplay's background daemon.
In addition to the standard media Player features, Everplay also lets you create playlists on-the-fly using Everplay's song queuing feature: the Jukebox mode. You can double click track after track and it gets added to the queue. iTunes has a similar feature, but you have to deliberately begin playing a song from within a playlist or else start all over again.
Other features not provided by iTunes include visual Player notifications, global hot keys, a mini controller on the desktop, Growl support, speech announcements, and a fullscreen mode with album browsing capabilities. Heck, the app even supports the Apple Remote.
When it comes to Last FM, Everplay lets you "scrobble" your music to Last FM, "ban" and "love" tracks, share 'em with your friends, tag songs or leave an artist or user a "shout" in their Last FM shoutbox. (To "scrobble" a song means that when you listen to it, the name of the song is sent to a web site -- such as Last.fm) -- and added to your music profile.) This means Everplay also lets you listen to personalized radio based on your musical preferences, tags, Last FM recommendations or similarity with a certain artist. You can even listen to your friends and other users' online music libraries.
With Everplay's Similar Artists mode, you can use your iTunes music library as the starting point for discovering new music based on similarity with your favorite artists. Double click an album in the Cover Flow view to begin streaming similar artists from Last FM.
One thing to note: if you don't like Cover Flow (though I do), you probably won't like Everplay's interface. And if you don't use Last.fm a lot, this may not be your cup of tea.
If you do use Last FM regularly, you'll appreciate the ability to combine your iTunes library with your Last.fm stream.
There's also Twitter integration, so you can tweet about your playlists. However, I've never used this feature.
Everplay requires Mac OS X 10.5 or later and iTunes 7.5 or later. Last FM web services requires a free Last FM account. Radio services might require a Last FM subscription (for residents outside of the US).
Macsimum rating: 8 out of 10 (IF you use Last FM)