Is there a tool that will remind me to execute some small task (like sending an email) in timespans of a week to two years?

Something that I may submit a task, like "email this person about launching a splinter community in one year" and have a reminder emailed to me?

It has to be some kind of web service using email, because email addresses are generally immutable and regularly checked in year-long timespans, and individual computer hard drives are not.