At the moment I'm taking a lot of medication and performing a lot of tasks while recovering from a serious chest infection. A couple of iPhone apps have been incredibly useful.
The first is 'Due'. This tiny app allows you to quickly turn on a timer or a set a reminder. I use the timers constantly. After gargling to wash out my mouth and throat after taking either my Ventolin or Symbicort I've been advised to not eat or drink for ten minutes - a few seconds with 'Due' and I have a timer. I also have to wait half an hour after taking my twice a day throat lozenge. Another quick timer. I don't use the Reminder function often, but it is easy to use when I do. It will even sync across your iPhone and iPad if you want.
The second app is 'tio'. This tiny app just allows you to log an event by entering a time stamp into an even log. The free version allows you three different events, the 99 cent version allows nine. I use it to log taking medicine and pain killers so I can quickly figure out if it's OK to take some more. I also use it to log each cigarette I smoke for two reasons. One, when I feel a craving coming on I can check the event log and tell myself "No, it's only been an hour since your last one." It also allows me to count the number I smoke each day, making it easier to ration and cut back. The app will email you the event log. Well worth the dollar.