On the ArchWiki, it is suggested, as a security measure, to run skype as a different user. My question is: would this make sense for the browser? I use firefox with NoScript and AdBlock, but also need to have Java and Acrobat Reader plugins, so... would the suggested approach be of some use?
So in theory running an application as a separate user may provide some security benefit in that in the event of the application having a security issue, the application may not be able to access data belonging to the primary user.
That said against that you need to weigh the usability problems of your browser not necessarily having access to data for your primary user. Also this approach only provides a benefit if you have relatively restrictive file permissions (e.g. it doesn't help protect files that are world readable/writable)