South Jersey Series Collectors - An excellent series books site with series checklists, books for sale, hints and tips for collectors, and a "Treasure Chest of Experts" where you can ask questions about your favourite series.
Series Book Central - Another great site. Lots of detailed information on many series and a really big book sales list.
Series Book Network - Many series lists; boys and girls series books for sale. Tom Hall Series Books - A collector's page, with lists and descriptions of many uncommon series. The Series Bookcase - This site has pages for some of the Grosset & Dunlap boys' series, like Tom Quest, Biff Brewster, Tom Corbett, Bret King, and Christopher Cool. Stratemeyer Syndicate FAQ - A concise and detailed history of the syndicate that created the books we love. The Billheimers' Girls' Series Book Page has books for sale and links to other series book sites. The Book Lover's Den - This site has a boys series book section that contains pages for the Hardy Boys and Tom Swift, as well as series for younger kids like Danny Dunn and Encyclopedia Brown. Home Page for Gary Holmes - Follow the Series Book Info link for some links and a juvenile series sales list. The Unofficial Stratemeyer Syndicate Homepage - A very comprehensive site about the Stratemeyer Syndicate and its series. Under the Attic Window - An archive of the series book e-mail newsletter.
SITES ABOUT SPECIFIC SERIES
HARDY BOYS
Boy Hardy - Resources for serious Hardy Boys readers, information about Edward Stratemeyer and the Syndicate. Gary's Hardy Boys Books - The author discusses the Hardy Boys "Canon". There's also a Hardy Boys message board. The Hardy Boys Drinking Game - An example: "Drink every time the Hardy Boys suddenly decide to fly somewhere, and don't seem to need any money." Great stuff here! Amazon.com carries many Hardy Boys books. This link is set for a search for "Franklin W. Dixon." Simon & Schuster, current publisher of the Hardy Boys.