One of our favorite TV shows is The Big Bang Theory and of course we enjoy the idiosyncrasies of Sheldon. Lots of interaction in the show takes place in the laundry room of the apartment building and I've seen Sheldon using a folding board for his shirts. It seemed a very efficient and clever way to get your shirts and T-shirts folded evenly. Little did I know that they are readily available and suggested for travelers to use.
Shirt folders are sold with boards that help you fold all the shirts you need uniformly and are stacked five to eight or more deep in a folder that closes around them and keeps them neatly packed in your bag. Here is one example available at TravelSmith and another at LuggagePros. The video below gives you an idea how it works.
Ah, but if you just want help folding those shirts, there is a make-it-yourself board. The instructions are found at eHow.
Or you could buy a plastic one like Sheldon uses. FlipFold makes several sizes.