In the past 12 months, we’ve seen the debut of several streaming music services, and while these have often be limited to running either on a website or smartphone, this week sees the launch of two similarly-named services that manage to bridge platforms.

First up is Rdio, a service created by the people who brought Skype to the world.

Like JB HiFi’s recently introduced streaming service, Rdio has a web streaming presence, but the offerings don’t stop there, with Rdio releasing apps for iPhone, Android, Windows Phone 7, and BlackBerry devices. Even the Apple iPad can jump on, as well as devices made by Sonos.

Rdio for iPad allows you to easily add albums to your mobile collection, ready to sync with your smartphone.

Similar to Sony’s all-you-can-eat streaming service “Music Unlimited” service, Rdio offers two subscription plans, a web specific plan for $8.90 per month with access available through the Rdio website, Mac and Windows apps.

If you decide to go mobile, you’ll need to upgrade to the $12.90 monthly plan, available for mobile devices, tablets, Sonos players, and even offline playback for smartphones.

The service launched this week with a seven-day trial service, giving you decent enough time to try before you buy.

More than smartphones, computers, and tablets, Rdio also supports devices made by Sonos.

We’ve been trying Rdio for the past day and have found that while the service has plenty of music to choose from, the apps could do with a bit of work. The service does offer a fairly wide selection of music, most of which can be found by searching, browsing new releases, or via the chart lists.

We’re a little confused about why there are no genre categories to search by, but the service does offer recommendations.

Rdio for Android

Offline playback works too, though Rdio doesn’t do it ridiculously quickly. At one point, we had only half an album synched, despite the app telling us it was all there.

Likewise, some songs and albums are listed as “not available”.  Given that it’s early days with the service, we suspect there are a few bugs to work out.

Then there’s the second service: Rara. Launched immediately after Rdio – and adopting a four-letter name beginning with “r” – this service is cross-platform too, but not nearly as versatile.

Rara offers web and mobile music playback, though at the moment, mobile options are limited to Android devices.