Synth Zone:A directory that covers synthesizers and midi controllers, plus relevant music software and support products.
Dancetech: Dedicated to making Dance music in home studios. Samples, synth usage tips and tricks.
Harmony Central: Synth Resources: Product news, reviews, original articles, free classifieds, software, local event locator, and links.
Jörg Schmitz Analog Synthesizers: German engineer offers schematics and turorials for a variety of analog synthesizers, with pictures of do-it-yourself models he has assembled, and linkes on microcontrollers and audio music technology.
Music Machines: Offers information on music technology.
Online Manual Archive (OMA): Collection of links to online manuals, schematics, and do-it-yourself repair information for musicians.
Synth and Midi Museum: Database with photographs of electronic musical instruments.
Synth Fool: Photo gallery of analog synths, including some schematics.
Synth Site: User reviews of lots of synthesizers.
Sythesizer.com: Arrick Robotics makes large synthesizer systems with analog circuitry including oscillators, filters and sequencer modules with wood, portable, and rack mounting options. FAQ, technical specifications.
The Analogue Synthesizer Resource/FAQ: FAQ/link list for Analogue Heaven mailing list. Useful links and information.
The Synthesizer Picture Archive: Photographs of new and vintage synth gear