Eu uso NoScript , mas coloque na lista de permissões qualquer site que eu realmente pretendo usar.
When you install NoScript, JavaScript, Java, Flash Silverlight and possibly other executable contents are blocked by default. You will be able to allow JavaScript/Java/... execution... selectively, on the sites you trust. You can allow a site to run scripts temporarily, if you're just surfing randomly, or permanently, when you visit it often and you really trust it. This means that NoScript learns from your own browser habits and tends to disappear in the background after a while, but it promptly comes back to save your day if you stumble upon a malicious web page.
When you browse a site containing blocked scripts a notification, similar to those issued by popup blocker, is shown.
Look at it or at the statusbar icon to know current NoScript permissions...