In spite of its flaws, when I was using Microsoft Outlook as my email client/personal information manage, Netcentric's Outlook add-on was my most successful "trusted system" (in David Allen Getting Things Done parlance). A year ago when I began a migration away from Outlook, I started looking for a web-based system that was cross platform and that would have the ability to also interact with a mobile device. I first used Nozbe, then moved to Toodledo. I've since moved to Gmail as my day-to-day email app and have struggled to manage these "systems" in parallel.

I just put up a blog entry exploring this here: http://wp.me/pJPKS-4B

Curious as to what others have come to on this subject...