4SquareAnd7YearsAgo is one my favorite reminder services. It checks my Foursquare account from the same day last year and sends me a mail with details on the places I had checked in.
They also operated a similar service for Instagram where they sent you the photos you shared on the same day last year.
4SquareAnd7YearsAgo has now announced a brand new identity. They have renamed their service timehop and Foursquare and Instagram functionality have been merged into a single platform.
And they have also added support for Facebook and Twitter. Now you would get one single awesome mail from your last year updates from all the four supported services!
This service has a lot of potential for growth and we assume that they would be adding support for more services in the future.