Songza, a free music service that somehow manages to get away not serving up audio ads, has updated their Android app with a feature called Concierge. Concierge has been available on iOS for awhile, and now Android users can get suggested music based on the time of day. For example, this Tuesday afternoon, the app offers expert-curated playlists for the summertime, needing an energy boost, or work/study music without lyrics. After picking your current situation, you can provide additional criteria to further tailor a playlist to your mood.
There are a bunch of different ways to explore playlists, including by mood, activity, genre, decade, or tailored based on your listening habits. Songza has all of the other standard features you'd expect from a streaming music app, like marking songs as favorites, and sharing tracks over Facebook and e-mail.
Songza for Android for is optimized for ICS and available for download at the link below. Just keep in mind that though the web streaming service might be available in your area, the mobile app might not be - that's the case here in Canada, anyway.