Email-your-friends reminder web application

This is an idea I've been juggling in my head for a long time. It's a web application where anybody who feels like it can sign up. Once you've signed up you write the email address of your friends and family who you usually forget to keep in touch with.

I'm confident to say I'm not the only one who has a long list of friends in different places on the globe where the best and sometimes the only contact is email. You write a little email every now and then to show your "interest". Or rather, to prove you haven't forgotten about them, because you don't want them to forget you. The problem is that as the list grows your email-sending-frequency stagnates with time. You might even remind yourself, standing in the shower, that it's been months since I last emailed my grand-father but by the time you sit by your computer you have completely forgotten what you reminded yourself of in the shower.

Here's my discussion for a solution When you've logged in you write down your friends email address and how often you expect to email this person. E.g. per.svensson@sweden.se, every 4 months; farmor_bengtsson@hotmail.com, every 3 weeks.

Then every 4 months and 3 weeks respectively you get an email that might look like this:

Dear Peter,
You should send an email now to per.svensson@sweden.se

Snooze this _one day_, _one week_, _one month_

This reminder is sent every 4 months, 
but from now on, send it every _3 months_, _5 months_.

_Canel reminder_

(where everything written in the example above with _ underscores are links that updates a database.)

It's just a loose idea and I'm promise nothing to myself but I think it'll be a useful application. It'd be nice to hear if more people out there have thought of it before and what they think. Has anything similar been done before?

UPDATE

This idea has now been materialised on RememberYourFriends.com