I got like 4-5 square feet of birch bark to play with... Any suggestions?

Birch Beer is an option if you want to toy with home soda pop production. http://en.wikipedia.org/wiki/Birch_beer

I think they also used to make baskets out of birch bark.

Birch tar

Or use it as kindling material or as a torch. It burns quite well.

this

Birchbark looks great right off the tree, but it's also a lovely surface for etching.  You can make baskets or winnowing trays (both of which I've done, and would look lovely etched).  I was going to make fun of the hat idea, but yoooooo that hat badger posted is one fine piece of headware (*gasp* YOU COULD ETCH THE HAT).  Would make a lovely quiver, if you have enough (ETCHED BIRCHBARK QUIVER *swoons*).  There are a number of folding crafts you can do with them, like birchbark stars (which I bet you could etch).  Roll them up into tubes and make little cups (etched cups).  Also makes lovely knife sheaths (guess what you could do to the sheaths).  Hair ornaments too, and they don't use much bark.  It just occured to me that making book covers out of them would probably be really cool.
There's also an art form called birchbark biting.  You literally use your teeth to bite patterns into the wood.  You can fold the bark to make radially symmetrical patterns.  I've seen people do it- takes practice to get good, of course, but the beginner can get results.
I'm sure there's more I'm forgetting.  And it's true- if it's rough or you have scraps, birch pitch is really awesome.