Alfa Clubs:
Alfa Romeo Association
Alfa Romeo Owners Club
Alfa Owners of New England
St. Louis Alfa Owners Club
Alfa Club Netherlands
Chicago Alfa Club
Club Alfa Romeo Svezia
Mark Battley's Electronic GTV Home Page has tons of information about 105/115 series GTVs. This is a great place to start to learn more about the GTV. If you are thinking about buying one, check out his Buyer's guide. After you have read the buyers guide, you will want to learn more about POR15 paint over rust.
Any journey of discovery must also include a trip to the source, so visit the Alfa Romeo Museum page. And there is always the Alfa Web Ring. Centerline, an Alfa Parts supplier, has a good page to help you identify various models. i Saluti, the newsletter of the St. Louis Alfa Owners Club has an excellent collection of feature articles.
Jim Hayes has a very interesting site which explains a little of what it takes to get into vintage racing. If you are a real speed-demon, you'll want to read Darren Besic's tale about the adventures of Bonnie at the SCTA Salt Flats Speed Trials.
Ben Dixion maintains The 1750 Page which has lots of interesting technical information and links about the 1750 GTV including how to build your own electronic ignition. If you are thinking of trying out various tire and rim combinations, check out Keith Tanner's Alfa Wheel Machine. Thinking about rebuilding your Alfa engine?
And finally, the AROC USA Alfa Romeo Links Page has a comprehensive collections of links to other sites. Subscribe to the Alfa Digest where you can discuss your problems (at least those related to your car) with other Alfisti.