Gootodo (now called Goodtodo) is the best solution I've found. It's simple, without categories, tags or priorities (other than sorting by position). The differe

Gootodo (now called Goodtodo) is the best solution I've found. It's simple, without categories, tags or priorities (other than sorting by position). The differentiators for me are: calendar-based to-dos. I can create a to-do that I don't actually need to act on until next week, and it won't show up until then. Also, awesome email integration, where I can forward an email to, for example, apr14@gootodo.com, and the body of the email will be attached to a to-do that shows up on that date. This is a fantastic way to get in the habit of emptying your inbox as well. Things you have to do don't linger there, you just forward them to your to-do list. Simple and elegant, and more than worth the $3/mo I pay for it.