Every one loves Ubuntu PPAs. They allow you to install apps from many external repos that Canonical doesn't ship in Ubuntu Software Center. Also, you can have updated versions of software installed in your PC that Ubuntu doesn't include for stability issues. But searching and managing PPA's is a hard task (I have over 50 PPAs in my Ubuntu Installation).
PPA Software Center is a great app that allows you to search apps in Launchpad PPAs and provides an interface to install the apps in your own computer. This app has been developed in Ubuntu App Showdown and works great in searching software in different PPAs using a single click.
You can install it in Ubuntu by issuing this command:
sudo apt-get install ppasc
There are a few bugs, use with caution.