Profile manager and Synchronizer is a useful Firefox add-on for those who use different profiles for their browser. This extension lets you easily create, delete , edit or backup a profile and can be synchronize between two profiles running on different machines, different location or operating systems like Linux and Windows by using Dropbox synchronization service.

Why use different profiles? Different profiles are useful if more than one person is using Firefox browser on a computer. Each one can configure Firefox as per their needs

It is also useful if you require multiple instances of log-in to services like Gmail, Hotmail and other accounts.

You can use a new profile to test a new extension you wish to install. Sometimes, install too many extensions in a profile may slow down the Firefox.

To synchronize between two profiles you required installing Dropbox and creating a new account with them. It is free for up to 2GB of online space.

More information and download is available from Mozilla add-on site.