You always have to have a pen and paper ready for great ideas that come about...
The Manuscript Books by Smythson of Bond Street are a classic treat. They come in a variety of colors and just make a girl look all pulled together at work or school. This brand is kind of on the pricey side, but if you deserve a little treat from yourself for some hard work at work or school, then this is it:) http://www.smythson.com/
For a sleek, modern notebook, try Muji, an inexpensive company that has a lot of fun everyday things at a very low price. My first time shopping at Muji was in London where they have boutiques all over the city. I know that Muji is sold in New York City at the MoMa store, or you could always go online at www.mujionline.co.uk to shop.
I love Jordi Labanda, and therefore I love all of the products with his work on it. This is a fun notebook with fashiony characters on each cover. I could only find this image, but it does the brand no justice...go to www.katespaperie.com to find more like this.