tl;dr: Download GrooveMac for OSX here!

Download it here!
I recently discovered an awesome, awesome program called GrooveDown, which lets you download songs on GrooveShark to your hard drive.
GrooveDown is written in Java and distributed as a Jar file, which means that it's very portable, but it doesn't integrate very well with OSX, an operating I'm stuck using until somebody makes the touch pad and wifi work properly in Ubuntu on the MacBook Air.
I've repacked it as a ".app" file, so it integrates better now. It has the OSX-style universal menu and it can be placed in the /Applications folder, so it'll show up on the launcher and it can be placed in the Dock. GrooveDown isn't open source yet, but they say they will be soon, so hopefully this will become merged into their master branch soon.
Download GrooveMac for OSX here! Source is on GitHub, as always.
How to Package Jar files as .Apps
This was really easy to do.
First step, download and install XCode. If you're reading this blog, you should probably already know how to this by now.
Then, open up 'Icon Composer'. Copy and paste your desired icon image into all of the squares. It'll resize them automatically for you. Save this as a .icns file.

Like this.
Next, open up 'Jar Bundler.' Select your Jar file and your .icns file. Also select all the anti-aliasing options and the Macintosh Menu Bar. Set any other properties you want to set under the 'Properties' tab.

Also, like this.
Then press 'Create Application..' and save your .app. And you're done!
Conclusion
And that's all there is to it! Enjoy GrooveMac!
Questions, comments? Leave them below!