I would say that many people who use web apps as to-do managers also have smartphones and want to use to-do managers on their mobiles. Plenty of to-do manager users may even only use them on their smartphones.
Lifehacker asked its readers and here are the results:
- Remember The Milk (22%)
- Others (20%)
- Google Tasks (18%)
- Things (16%)
- Astrid (16%)
- Omnifocus (9%)
It would be interesting to know, how many people rather use paper and pen when on the road. Probably paper would outscore Remember The Milk.