We found this paper and thought it was pretty neat. It really does sparkle and shimmer. The polymer is infused with a silver metallic sparkle that is seen through the lighter portions of an image. For use on light colored fabrics as the shirt color will show through your design.
Just print an image on the paper, use a heat press or iron to iron it on your t-shirt, and voila you've got a little bling on your t-shirt. Keep in mind the "sparkle" is a metallic silver, so that will show through any image you use. It's not stretchy, so avoid rib knit fabrics, but it works amazingly well on jersey. Expect a bit of a "hand" on the fabric as the polymer is a stiffer than other transfer papers.