I have to admit that I'm a little late to the seam binding party. I've seen it used everywhere but could never figure out how you could ever have enough of it for a project because the only kind I've easily found is a small portion in a small package. So, when I was working on some slightly more "fancy" clipboards recently and I really wanted to add some pretty seam binding (a good match for the sewing patterns and all), I did a little internet research and found a good source.
By good, I mean there's enough of it to really do something with (100 yard spools), it's not too expensive, and it comes in a crazy array of really, really good colors (those slightly off colors that I love so much and can never find). The brand is called Hug Snug and, since the label says washable, I think you could even dye it if you wanted to. I bought mine on ebay from a sewing supply place called zipperstop. The color I used in the clipboard projects is called "cruise beige".
The clipboards I made are going into my lollishop as soon as I get a chance. Lollishops is described as a "frou frou friendly marketplace" and I wanted to make some frou frou-ier clipboards. I painted the boards off-white, added a little watercolor to the dress images on the back of the pattern, attached a fluffy amount of seam binding, and a sweet little heart. Jump over to the shop here to take a look.