However, after a few years of holidays, birthdays, postcards and thank-you notes, I've just got a big mess.
I used to tape each item to a sheet of computer paper and then put it into a plastic sheet protector and kept them all in a 3-ring binder. Two problems with this: 1) you have to do some work to go through and read them again (and yes, I like to review what someone wrote in my birthday card years ago) and 2) I feel like I'm wasting paper, the sheet protectors and tape.
Then, Voila! Thank you PINTEREST! (Ha, imagine that). Someone posted about what to do with wedding cards - they put some holes in them and made them into a little booklet.
And that's just what I did. I took all my (and Grizz's... at least the ones he has kept around) birthday cards, Christmas cards, post cards, thank-you notes, shower cards and wedding cards, and made them into little booklets. So now on every birthday, I can look through old cards and add the new ones. Every Christmas, I can set out the booklet(s) on the coffee table and flip through it. Every time I'm having a bad day, I can read through the thank-you notes :)
Now, I don't have gift bags of wedding cards laying around. We'll eventually have a wedding "trunk" to keep all the memories in, but until then, all of these card booklets have a home in a dresser in the 2nd bedroom (surprisingly, there's one open!)