Chrome plugins pose a HUGE security problem. This one, for example, gets access to your GMail account. Do you want that? What else could this plugin do since it can read your email? Do you trust the author not to steal your GMail cookie?

Are you installing this at work? What kind of trade secrets could you potentially leak? And how does it affect your corporate compliance requirements? If your email is subject to HIPAA regulation, then you may be leaking protected health information. That's pretty bad.

I, for one, rarely install plugins. I've written plugins for my own amusement that can do some very bad things, and it's just too easy. Think twice people.