Update: I’ve been using ReminderCountdownPro for years, and it’s still the single most used and most useful app on my phone. Pay the 99 cents and make your life a bit easier 🙂
I use ReminderCountdownPro all the time: Birthdays, doctors appointments, anything that's coming up that's important to me, I just create a timer for that event. This is a very practical application and I probably use it more than any app on my phone besides email and messaging.
One of the coolest things you can do is set up a timer with your birthday, kids birthday, wife, or whatever, then the timer will show your Exact age in seconds, minutes, hours, days, years, etc... So cool!
I just had one complaint: it wasn't possible to arrange the reminders. New reminders appeared at the top of the list, and the older ones were moved down. But that was fixed with an update so now ReminderCountdownPro is perfect! I love ReminderCountdownPro and highly recommend it!