The necessity of auditing mechanisms for smart cards is currently under thorough investigation. Both current and future real world applications impose requirements which suggest the storage of sensitive information in log files. In this paper we present various applications that demonstrate the use of audit logs, justifying their practical advantages and disadvantages. We propose computationally practical methods for creating and maintaining such log files in the light of the limited memory of smart cards. We conclude with a brief discussion of design principles for future implementations and guidelines for further research.