The smartphone is an acknowledgement of the way that life has changed. It means that we are never out of the office, should never be without a map, or the ability to contact someone - through any one of a handful of means.
It should also mean that you never forget to do something important. However, we all do, and thankfully there are apps that can step in to remind you of what you are supposed to be doing and when you should be doing it.
The Astrid todo list, or task organiser, fits this role nicely, it is free to use and as a business tool lets users do things like share meeting agendas and minutes. Its interface is clean and easy to use.