xReminder Pro from Vladimir Kulemin at Duality Software is such a program. I've been using it for years, can't live without it, and heartily recommend it.

There's a very small one-off charge for this simple little reminder program. It pops a reminder up onto your screen (with a sound) whenever you want it to. It can remind you of birthdays, it can remind you to take the bins out every second Tuesday - Whatever...

If you'd like to be a super organised person, this is the program for you. It's one of a number of handy programs on offer from Duality - To check them out, click on this image: