Your client may wish to share login information to websites they use to allow you to make updates or shop on their behalf, for example.
Rather than emailing across the login information and risking a security breach, we've often suggested LastPass as a useful tool. We now have an alternative tool for you to suggest to your clients.
www.accessurl.com is a Chrome extension that allows a virtual assistant to log into sites like Amazon or United Airlines as the client, without needing to know the client's username and password.