ReminderFox is a Firefox extension that adds a scheduler and to-do list manager to Firefox. ReminderFox sits in the bottom corner of Firefox and lets you manage your to-do list, and it displays any reminders you set. Although it has an alarm and calendar built in, ReminderFox is not meant to replace your existing calendaring system. I find it very useful for giving yourself daily reminders and using the alarm feature to help with time management. Also, since ReminderFox works with Firefox, I find it particularly useful to manage the tasks that can only be completed on-line. For example: checking bank and credit card statements, visiting a website (lifehack.org!), sending out pictures, etc.
ReminderFox is an extension for Firefox and Thunderbird that displays and manages lists of date-based reminders and ToDo’s. ReminderFox does not seek to be a full-fledged calendar system. In fact, the target audience is anybody that simply wants to remember important dates (birthdays, anniversaries, etc) without having to run a fat calendar application.
ReminderFox – [addons.mozilla.org]