I toyed around with Songbird today; it is an extended version of Firefox that adds the ability to play songs, listen to the radio, watch videos, etc, while still being a full-featured web browser. I am amazed at how well they were able to skin Songbird to look nothing at all like a standard OS X app. They are obviously much better at Cocoa than I am; I hope to get to their level someday.
As you can see, it looks pretty nice:

As for the functionality itself, it is a pre-1.0 version so expect some rough edges. For instance:
- It looks like the relatively powerful Firefox bookmark window has been replaced by a weak, single-level bookmark list on the left navbar.
- Searching also doesn’t work as expected. By default, when you search for anything on Google it searches for Music only, so you need an extra click to search the web. Also, it doesn’t remember that Google is the only search engine I want to use; it remembers across restarts, but gets reset when I click the bookmarks on the left.
- CMD-n creates a new playlist, not a new browser window; and CMD-t is defunct.
- I couldn’t figure out how to install any extensions without going to the command line. In fact, even from the command-line I couldn’t get the 1Passwd extension to load. I’m still not sure why.
From this list you can see that Songbird is currently focused on being as good as iTunes, and has sacrificed the web browsing experience to accomplish this. I hope in future versions they improve the web browsing side of things.
When Songbird 1.0 is released it is definitely something you should checkout.