You could go the smores route by layering the graham cracker crusts with maybe a chocolate ganache or a chocolate mousse type thing and then frost the cake with marshmallow fluff.. or top it with mini marshmallows and take a creme brulee blow torch to it.

What about an icebox cake using graham crackers as the base? There's one in the popular links bar right now.

Eat Live Run posted a graham cracker torte a while ago that looks really good!
http://www.eatliverun.com/graham-cracker-torte/

This no-bake Boston Cream Pie Strata is multiple graham cracker layers with other good stuff in between. I imagine that when the strata sets up in the fridge and the graham crackers absorb moisture from the fillings it would taste very much like graham cracker crust...times four.

http://www.thekitchn.com/-cookbook-recipe-137474

I made the strawberry icebox cake that's in the side bar right now (http://www.thekitchn.com/summer-recipe-nobake-strawberr-117900), and it's delicious. I'd highly recommend it!

Ok. I'm voting for the Boston Cream Pie Strata :) Follow the link---it almost made me faint! Yum to the 10 power.

I think the other ideas are good, but they all sound like they focus on graham crackers--not graham cracker crusts. (It sounds like what he loves is graham cracker *crust* specifically.)

I'd go a simpler route, similar to what you were thinking--make two graham cracker crusts in sheet pans, use one as the base, add a thin layer of filling (cheesecake or chocolate ganache or lemon curd would all work well), and a layer of crumbled graham cracker crust on top. Maybe a dollop of whipped cream if you're feeling fancy. It really focuses on what your friend loves and doesn't get muddled with desserts that are just graham cracker centric,

I made the Boston Cream Pie Strata for my husband's birthday 2 weeks ago because he loves Boston Cream Pie, he LOVED IT!! It is very graham crackery, especially after it has set up in the fridge for a day or two. The custard & chocolate frosting are delicious. Highly recommend this recipe:-)

While no one in their right mind would turn up their noses at these delicious ideas, I agree with Oscarmama. Part of what makes graham cracker crust so good is the extra butter and sugar. Until I saw this post I had forgotten that I've been known to make a double batch of graham cracker crust because I continually "sample" it.

Ooh, that graham cracker torte sounds great! But honestly, if it's crust he wants, I would make a double or triple recipe of crust, bake it in a springform and serve slices. I would totally eat that!

I'm thinking of his love of graham crackers like a person that loves vanilla wafers...I can promise you the vanilla wafer cake is delicous. Just use graham crackers instead. It's also very simple. It's homemade, the Duncan Hines part is just an advertisement for the frosting.
http://www.duncanhines.com/recipes/cakes/elaine-campbell/vanilla-wafer-cake

I have a graham cracker cake recipe that I always asked my mother to make for me. It's very delicious and Its one of those cakes that you run to when you need a special cake.

6 egg whites, 1/2 tsp salt, 6 egg yolks, 1 1/2 c. sugar, 1 tsp vanilla, 2 tsp almond extract, 2 cups grahm cracker crumbs, 1 cup finely chopped walnuts.

beat egg whites and salt in a large mixer bowl on low speed until foamy. Beat on high speed until stiff but not dry.
beat egg yolks in a small mixer bowl on high speed until thick and lemon colored.
beat in sugar gradually on high until the mixture is thick and forms ribbons, about 10 minutes.
Beat in baking powder, vanilla and almond extract.
Fold egg yolk mixture, graham cracker and one cup of walnuts into egg whites
Pour into two greased, floured and wax paper lined 9" round pans

Bake at 325 until tooth pick inserted into the center comes out clean about 25 minutes. Cool ten minutes and remove from pans

serve with whipped cream and strawberries