The Interactive Way To Go: provides a great interactive introduction to the rules and basic strategy of the game.
GoProblems.com: a good place to find go problems for players of all levels. Doing go problems is one of the best things a players can do to help improve their game!
American Go Association: The AGA website is a great place to keep up on the Go happenings of the USA as well as the rest of the world. You can find everything you could need here. News, club listings, links to go equipment retailers, and so much more. Give it a visit and take a look around!
Games Galore: While there is a large variety of equipment for sale online through many retailers, Games Galore is a great option for sourcing your equipment locally. Even better is that they are generous enough to provide us with table space for hosting our club meetings each week, making it a great time to take a look at the equipment they have available or can possibly have ordered for you!
AGA Equipment and Supplies Page: The AGA website has a great directory of online retailers of Go equipment. Check it out if you're looking to get your equipment online.
Online Go Server (OGS): A browser based Go server that doesn't require any kind of desktop client to be installed. It has a very nice interface that is very easy to use. It even provides game review tools that allow for easy game analysis and after-game group reviewing. The website is mobile-friendly and also has an app. There is a very active community of players making finding games very easy.
KGS Go Server: An easy to use go server with a desktop client that doubles as an SGF editor (SGF's are the file type of saved games). Has a good user base of all play levels, making it good for players of any strength to play on.
Internet Go Server (Pandanet): A well established Go server that can be played through a desktop client.
All these servers are great places to play Go. The KGS Server is probably the most recommended for newer players, and the OGS Server the best overall server to play.