Following is a Firefox extension I have been using which makes signing up/logging in for any site very easy with a few clicks and no use of keyboard.
Inform Enter - https://addons.mozilla.org/firefox/673/
Very small extension ... u just put some commonly used usernames/emailids/passwords in its options and u can choose the same with your mouse in any form space on websites. You can put multiple usernames etc so its awesome if you signup/signin to sites/forums frequently.
I have been using this for last 2 months and havent typed anything apart from captchas to signup. Also very user-friendly so all n00bs can also use it.
Note: I am not the author/connected to this ext in any way. Just that I think it'll make everyones life a li'l easy arnd here so pimping it.