Anyhow, if you have a CD or a single file which contains few lossless audio tracks within itself that has to be split or Extracted into mp3 or Flac under Nautilus file manager as easy as right clicking on it... then Split-lossless is a very valuable little tool without a doubt!.
One good thing about Nautilus is that you can easily expand its functionality by using simple commands/codes called Nautilus Scripts. Although, even without learning about programming Java/C++, etc... if you're familiar with bash-commands (you know those standard commands that we put into the Terminal such as "su" or "sudo" for instance), once you get familiar with its coding style... we can easily use these already existing bash-commands together in a single "script" and create a command of your own!.
Anyhow, if you don't have time for that sort of a thing :) and simply want to know how to install the Split Lossless into your Nautilus... then start your Terminal window and enter the below command to install it in Ubuntu 11.04 Natty Narwhal (I think it should work on 10.10 and 10.04).
sudo add-apt-repository ppa:cokicd/split-lossless
sudo apt-get update
sudo apt-get install split-lossless
Once installed... simply right-click on your .cue file and from the menu that Lossless Split adds you can choose your codec (flac/mp3). And the cool thing about it is that, all the meta information such as Album name, Artist, Track name, Year, etc are automatically fetched for you!, a huge time saver.
Depending on your needs, you can choose the best possible audio bitrate, a built in progress indicator, a preview before splitting is done, automatic notification when done + you can even tell it to automatically delete the source file as well.
Seriously... it may be a script... but this is one of the impressively useful tool for those of us who deal with audio related "stuff" without a doubt :).