Since the the summer term 2009 the university calendar is available online under JOGU-StINe. You can research all lectures and courses, register and check-out as well as organize your personal time table. For this you need a current ZDV-account.
Further useful information for the oragnisation of your courses:
For legal reasons this information is only available after loging on with a university account. By downloading the data you agree to use it only in the teaching context it was provided in and not to distribute it.
Should you have forgotten your password, you can apply for a new one here.