Is there a way to search though LaunchPad's PPAs for a certain package name? For instance if I was looking for PPAs with Firefox packages I could search for "firefox" and retrieve a list of all the PPAs which contain a firefox package.
You can search for PPAs matching software or package in the following link
Y PPA Manager is a standalone programme that can be used to search PPAs for a certain package. Once some PPAs are found, you can easily list the packages and see what other packages (and their versions) that PPA provides. It also allows for much more precise ("deep") searches than the Launchpad web interface.
You can install the package from the ppa:webupd8team/y-ppa-manager PPA.
ppasearch looks handy for command line environments.
https://launchpad.net/ubuntu/+ppas?name_filter=gjots2 will show you PPA that ship the gjots2 package, for example. No need to install any additional tools.