I've been using Tres Cosas for a week now, and have really been enjoying it. In particular, I like it because it 1) helps me focus on today and tomorrow, not the far future or past; 2) is keeping me well-rounded, not thinking of productivity as a work-only thing; and 3) is designed with such simplicity that I'm not carrying around the plaque of todos/reminders that build up over time. I highly recommend checking it out.