I've been using the Photojojo Photo Time Capsule for a few months and am really liking it.
Once you sign up and link to your Flickr account, you get an email twice a month showing you an assortment of pictures you took that week, a year ago. Look at how simple it is:
A few hours ago, I was reminded that this time last year I was reading too far into things I saw around the city:
There are other neat little features like being able to share your Time Capsule on Twitter and writing a message to yourself that will be included in your Time Capsule the following year.
I like how simple this tool is, and how excited it makes me each time I get an email from them. I read my journal from "this day last year" every day, just to see what I was up to... the Photo Time Capsule plays into the type of nostalgia you get when you stumble upon something from an earlier time in your life even stronger than reading text, I think. Give this a shot, it's free too.