Not possible to store to do's and other information in bookmarks, but rather on file Rated 2 out of 5 stars
It would be reliable if it was possible to store data (to do's...) in bookmarks and synchronize it with X-marks.
Automatically without need to import or export to backup.
But instead all data must be manually exported and imported. In the event failure or other things, living the last backup/export which might be three months old to be what you might be left with in case a crash.
So not too reliable to store data or rely on, but good design.
Ensuring that there is no data loss is an important part of any reminder or ToDo system. While ReminderFox currently has no server-side storage of its own, it offers full synchronization support so that you can synchronize reminders with other computers, or just use it to keep a remote backup. See the details here: http://www.reminderfox.org/documentation-user-guide-sharing-reminders/#r5
Alternatively, many users have used Dropbox to get automatic backup by simply storing their reminderfox.ics calendar file in the Dropbox folder.