It appears Clickpass' SSL certificate is expired and so clickpass buttons no longer work by default. It will show a blank space where the button should be until they fix it.
In the meantime, you can log in one of two ways:
1. Go to the Clickpass site and get your browser to accept the certificate anyway.
http://www.clickpass.com
Once you've done this the Clickpass button will show up properly on our site.
2. Use a password.
If you don't already have a password set, you can get a recovery password here:
http://www.skritter.com/recover
Just put in your username and it will send you a temporary password to your email. Then you can set a normal password.
Sorry about this guys. I don't know what's going on over there if they let their SSL certificate just lapse. If they don't fix this soon, we may just have to drop support of Clickpass.