After the Penny Pinafore Hack post I had a few people ask about good sweatshirt and ribbing sources. Those materials can be a little tricky to find, especially good quality ribbing. A ribbed knit is not the same as ribbing and I get a little cranky when some fabric retailers mislabel things. So I've complied a short internet list of US suppliers for these fabrics. (Sorry foreign readers) I have not purchased from all these sources, but all of them will provide swatches.
Fabric.com - They have an organic cotton line and a 80% polyester/20% cotton line. Both come in a variety of colors and natural if you like dying your own fabric. I have bought the organic sweatshirting and it's really great.
NaturesFabrics.com - This company stocks the most printed sweatshirt material I've ever seen. They also stock solid colors and a natural color for dying in both cotton and bamboo blends. I've bought some solid black and found the quality to be pretty good. The fabric pilled a bit more than the fabric.com fleece, otherwise the fabric preformed well.
ResponsibleWears - I just ran across this Etsy seller and find her hand dyed sweatshirting to be really attractive. She uses organic cotton sweatshirting. Great for those of us who love the look of hand dying but don't have the space to do it ourselves
TheRainShed.com - Downside of this site is that you have to call to order. Upside is that they sell many solid colors of 80% cotton 20% polyester sweatshirt fleece. There are a few colors of 100% cotton fleece and some french terry thrown into the mix.
Harts.com - Carries 10 colors of 50/50 polyester cotton blend ribbing. This is the tubular knitted kind with some body to it. Just what you want for a sweat shirt.
SeattleFabrics.com - Outdoor fabric suppliers are great for beefy ribbing. Seattle Fabrics carries 15 colors of tubular nylon/lycra ribbing and 3 colors of an even heavier ribbing for leather jackets.
TheRainShed.com - The rain shed also carries A LOT of ribbing. They have in stock nylon/spandex yardage, 100% cotton yardage, and fully fashioned cuffs. I'm going to be buying some swatch sets from them.