Silicon Empire is a free cross-platform CD and DVD burning software that will help you manage all your optical discs via a well-designed user interface. With Silicon Empire, you can burn CDs, DVDs, blu-ray discs, erase DVDs, copy CDs/DVDs, etc. You can also use it to mount/unmount iso images using Silicon Mounter.
To install Silicon Empire on Ubuntu 11.04, download the appropriate deb package from here:
AMD64 | i386
Use then the dash to launch Silicon Empire:
Silicon Empire's screenshot