Designing a new T shirt Design

I always think that designing your own T Shirt is cool thing to do, it is like you wear your attitude and you can write whatever you want on it and also add a custom Design. Now a days there are many companies who have the website where one can go and create a T shirt with their own Design. I have some ideas in my mind and will design it soon. More than the design I like the T shirts with good messages or quotes. Like big brother tshirts, they have really amazing collection of cool funny T Shirts. I wonder if some company would come up with customized Shirts, Pants and other Garments. I would most probably order some T Shirt in Black, which is my favorite T shirt color. I think I have 5 or 6 black colored T Shirts.