Based on prompting from a point made in this great article, I extended the System logging Known plugin that I wrote previously, to include a visual security log.
This log shows a user by user security log, showing login/logout and login failure attempts for each user’s account, plus a global log visible to the administrator. This provides a visual way for you to keep track of when, and from where, your account has been accessed, and hopefully give you tools to spot erroneous access attempts (for additional security you should totally check out my two factor authentication plugin as well).