If you are like me, you probably have accumulated a ton of math and literacy printables to be used in your centers. Storing them in ziplock bags just won't do. For one, they are too big for the bags and all those little pieces fall out. I found these gems at the Dollar Tree and was ecstatic. They are polyvinyl envelopes with snap closures. I know you can find them at Target too, but they are a little more expensive. At the Dollar Tree they came in packs of 3 in red and blue. I'm using red for Language Arts, blue for Math. They have a snap closure and hold my centers perfectly. I used the label maker to create my labels and store them upright in a plastic container. At some point I will probably adhere a label to the front listing all the centers inside each envelope. For now, I just clip each center together. For the small cards that some centers have, I use small ziplock baggies and binderclip them to the larger sheets.
TIP: print out the directions for the center with the name of the website/blog you obtained it from. This helps if you lose any pieces, can't remember how to play, or want to make another set in the future.