There are lots of questions on the Internet about possibility of keyloggers being installed on the public computers and the use of Outlook Web Access (OWA) on such machines.
Let's presume that you are using public computer in an Internet Café anywhere in the world. You want to connect to your company's e-mail by means of Outlook Web Access interface.
Since you are not the administrator of the machine or have higher privileges on that same computer, you are not able to install programs on it. It means you have to use the computer AS IS.
You can't prevent keylogger from collecting your data, since you lack the privileges to do so, but your e-mail system can use two-factor authentication as a form of letting the users in.
Two factor-authentication is a system wherein two different methods are used to authenticate. Using two factors as opposed to one delivers a higher level of authentication assurance. Using more than one factor is sometimes called strong authentication. (Wikipedia, 2008)
One Time Password (OTP) tokens can be used to enter random number found on the token as a first factor of authentication. If the first factor authentication is positive then the usual OWA domain\username\password authentication is used as a second factor of authentication.
Since one time password is used only once, keylogger will log already old data thus preventing possible intruder to use it again.
Keylogger will of course log your domain, username and password but such data will be useless to certain extent as your online services would be probably protected with two factor authentication and OTPs.
Since you are now NOT the only owner of your username and password, domain password expiration policy IS A MUST and passwords must be changed constantly.
Your data could be stored by keyloggers on the public machines even if you are using On-screen keyboard. Current keyloggers have even built-in option to save screenshots thus making any other authentication option (for public computers at this very moment) than two- or more-factor, unable to prevent possible intrusions that would use logged data.
Wikipedia (2008) Two-factor authentication. Available at: http://en.wikipedia.org/wiki/Two-factor_authentication (Accessed: 11 April 2008).