Matt's Disc Golf Links
I only intend to list sites that I have personally visited and enjoyed. The vendor sites are places where I actually bought merchandise and was satisfied with the product and service.
This is where I buy my discs online. Tom Monroe has been playing Disc Golf and winning for a long time (PDGA #33 multiple World championships won!). He will give you personal advice on what discs to use to improve your game. His volume discount prices are the best you will find online. I know because I searched and purchased from several online vendors before I settled on Tom. You won't be disappointed and no he isn't paying me to say any of this.
This is the place to start if you are looking for disc golf information on the web. It has a ton of great links listed under resources.
Look for a course near you or where you are going at the comprehensive list of courses now maintained by the PDGA.
Another great place for information. Join the sport's professional organization and help disc golf grow.
I used to link to Brian Sullivan's Disc Golf Website but evidently he is too good to exchange links with the likes of me. You can find him somewhere on the Disc Golf Web Ring linked at the bottom of the page. That's all the courtesy he gives me now so I'm returning the favor. 
Links to disc golf and other disc sports information.
More to come later