Last week GrooveShark released a really cool new widget-based playlist creation tool to take your GrooveShark and GrooveShark lite created playlists off-site. The new designer which lets you put together a playlist with tracks from both the GrooveShark's online catalog and your hard drive.
If you've been looking for a proper replacement for the currently-defunct Muxtape, this is even better. While I've been fairly impressed with solutions like Mixwit, a hybrid system like this lets you search for music you don't have, while letting you upload tracks that might not be available for streaming. GrooveShark's marketing rep Steve Spalding tells me this system is entirely sustainable since the company's got streaming deals in place with SESAC, ASCAP, and BMI, meaning the copyright-protected tracks you've uploaded won't result in a take-down of your music.
I've embedded an example widget below with a mix of tracks both from my laptop's music collection and a few tracks from GrooveShark's catalog. Worth noting is that the current system only accepts MP3s, meaning AAC or WMA tracks you've ripped in iTunes of Windows Media Player won't play. I'm told support for FLAC and other lossless formats is on the way. In any case, if it's a big name band or a popular track you're likely to find it with GrooveShark's built-in search tool.
Another thing worth noting is that the widget editor seems to be duplicating songs for no reason. After publishing a playlist I've had songs duplicate and triplicate with no explanation whatsoever, which you can see in action below. It's an annoying bug (especially with larger playlists), and hopefully it's fixed soon.
Update: GrooveShark developer Skyler Slade wrote in to let us know the duplicate bug's been fixed (see the comments), which you'll now see in the playlist below.