[ Thanks to Silverwave for this link.
]
“A new command in Karmic makes it easy to add a PPA
repository and its key, all at once.“Code:
sudo add-apt-repository ppa:ubuntu-mozilla-daily/ppa
“Now you have access to Firefox-3.6b6pre and Firefox-3.7a1 daily
build packages for Ubuntu. These packages install in their own
directories so you can use 3.5/3.6/3.7 side by side.”