A vendor of kits and blanks, as well as many other turning related merchandise. Arizona Silhouette carries some very nice higher end kits. They have very responsive ordering procedures and usually ship within a day.
A free and open organization for penturners to share ideas and experiences. A forum, photo gallery, and extensive library provide a wealth of information for all levels of experience.
Not a supplier, but rather a forum for pen turners. This site has many relevant discussion groups, as well as galleries and how-to's. I recently joined this group under AmazinglyRustic, and I find the group a must for new resources and information.
Woodcraft has a good selection of pens and materials. I tend to purchase many kits from their local store in Toledo, Oh. This gives me a chance to see many of the materials first hand and pick the ones that I think will turn a good pen. I also took my first lathe class at the local Woodcraft store which got me hooked on turning pens. If you have a store near you, please stop in and see if they offer a pen turning class, it is an amazing amount of fun!
Penn State Industries (PSI) has a wide selection of pen kits and exotics. This is a great store with good prices and fast shipping.
Augum's is a pen parts supplier. They carry a few Penn State Industry Kits and some kits under their own name at a reduced cost. They have very prompt shipping and great sale prices.