Mobile music while traveling is a problem. Most people don’t sync their entire selection to their phone, and if they do, what if they want to download and listen to a new track or album?
Enter Spotify (Free – $10/month). Ubiquitous in Europe for the last couple of years, and it has expanded to the US a few months ago (currently available in Sweden, Norway, Finland, the UK, the US, France, Spain and the Netherlands). Spotify is a streaming music service, and it’s free for 10 hours per month using the desktop client, and $5 for unlimited streaming. They have anywhere from 15-30 million songs available in their completely legal catalog, and their client works well (read: much better than iTunes).
Now, to the mobile part: For $10/month, you can stream music to your mobile (iPhone, Android, Symbian, Windows Mobile, WebOS) and then sync playlists, songs, and albums to use offline! As long as you sign up for your Spotify account from one of the spotify-launched countries, you can go anywhere with the app. So find some Wifi in that Costa Rican coffee shop, play some tracks, make some playlists, sync them offline (up to 3,333), and then feel free to roam the world with that music, no need for an internet connection.
Spotify looks to be the best option for traveling audiophiles right now, but there is another hope. Google Music allows you to store 20,000 of your own tracks for webapp access, and gMusic ($1.99), an unofficial iPhone app for Google’s service, has surfaced. There are caveats though:
the offline mode apparently only works when your cell radio is on (a weird bug that hopefully gets fixed soon), and (Update 10/19: Found out that gMusic 1.2 should fix the offline mode problem, and it currently in review for the App Store) Google Music is only available to US customers, but if you game the system for an invite, according to reports, you can use the service to your hearts content.