MantisBT is a popular open source issue tracking system.
Mantis was designed primarly as a tool to manage software development projects, particularly to manage bug reports and enhancement/support requests. As such, most (if not all) tickets are created on-demand, as someone reports a bug, or request support or enhancements. Mantis can be used as a more generic issue tracking/management tool. There are multiple scenarios where Mantis would be a handy tool to have in your arsenal, but by virtue of its intended use, it is missing one important capability, scheduled tickets.
MantisScheduledTickets is a Mantis plugin that allows for tickets to be created automatically, based on custom-defined frequencies and templates.
You first define "frequencies" that make sense for you and your specific context/scenario. Next, you define ticket "templates" and associate them with projects/categories, as well as frequencies. All you have to do now is sit back and wait... Tickets should now be generated automatically, based on the frequencies that you defined. As an added bonus, you can even have these tickets assigned to a particular user!