Medication Tracker is an application that helps you keep track of up to 4 medicines at a time. You can keep track of how many times you have taken medicines on any day, by clicking on the buttons on the first screen, as and when you take them. You can also set the medicine names to whatever you want using the Settings screen.

This application is free till 31st March 2009.

http://appshopper.com/medical/medication-tracker