For Thanksgiving this year I made a few pies and I took a some pictures so that I could share how to make a traditional lattice pie crust top. 
A lattice top is a classic that always looks pretty. It seems like it could be a lot of work but it really isn't. Here are some simple instructions to try it if you've never done it before.
To start, roll out the top crust (it is easier if the dough has been chilled first) and then cut it into strips of an even width. I just use a knife to cut my strips, but you can use a pastry wheel or pizza wheel as well.
Once you have the strips all cut, drape a strip across the middle. Working out from the center, lay out the strips on one side and then the other until the whole pie is covered, spacing them one strip width apart.
Next, fold back every other strip on the top of the pie. Make sure to fold it back a little more than halfway. Lay a strip across the middle of the pie, perpendicular to the other strips.
Now fold the strips back down over the middle strip that you just laid down. Every other strip will be on top or underneath it. This is the start of the lattice.
To make the next lattice piece, fold back every other strip again but this time you want to fold back the ones that were underneath the middle strip. Lay down another strip of pie dough and then fold the strips back down.
Repeat the same process of folding back strips, laying down a perpendicular strip and folding the strips back down, alternating which strips you fold back each time. Once the pie is covered in one direction, perform the same process on the other side of the pie.
To finish simply trim the ends of the strips. If you want you can leave it (just pinch the strips down into the bottom crust to seal it) or you can make a fluted edge.
That's all there is to it. It looks quite fancy but it is simple to do in less than ten minutes. Easy as pie!