Keyloggers are a very harmful malicious scripts, that capture keystrokes and spy on your private data and passwords. These programs maliciously install themselves, and run without the users being aware about it, making it a huge security threat.
There are several methods to thwart keyloggers and many banks do provide users with a virtual keyboard facility using which they can enter their secure passwords.
However many email sites and other websites which ask you to login before accessing the service, do not have such features in place. But if you are a Firefox user, you can run a Greasemonkey script called Virtual Keyboard Interface, which will provide users with a virtual keyboard to fill in text fields, password fields or text areas.
Once you have installed the Greasemonkey script, double click on any text or password field to display the virtual keyboard, use the keyboard to type in your data and thwart keyloggers.
You will require the Greasemonkey Firefox Extension before you can use Virtual Keyboard Interface, you can download it from here.