I'd avoid the skpye tool bar not sure what use it is to most users to be honest who for actual telephone numbers still call using a phone of some sort especially if a local number..
Some add on's such as Adobe acrobat and office type software functions many find useful.
Internet explorer in 9 has a great function where it highlights how much time a addon will add to the start up speed but of course that's only one part of having a add on loaded into your browser..
On Firefox some addon's totally change the use of the browser and make it a far more (for the particular user) useful tool. Pop up blocker, forcing tls connections, link checkers, translator tools, checking the connection is what it says it is...
So my point would be don't say never but more would I ever use or need the add on?
