Useful links

Soldering tips - Simple step-by-step tips about DIY soldering.
Measurements in electronics - Simple and useful tips measurement and tests of electronic components.
Make your own Printed Curcuit Board - This is the most famous method - using a laser printer/copier and the home iron.
Make your own Double-Sided Printed Curcuit Board - Get a quality double-sided PCB in minutes.
Handle and store electronic components - Simple tips for safe handling of electronic components.
CSA93 s912 amlogic firmware - Fix / unbrick CSA93 s912 amlogic 3GB media player, instructions, download, firmware update.
Online Electronic Circuit Simulator - very intuitive, no installation needed
Circuit Simulator Applet - can work offline, you need Java plug-in installed
Coil Inductance Calculator - fast inductors calculation
Circuit handbook - well organized Russian site (in English) with electronics basics and original solutions - Instructables is a place that lets you explore, document, and share your DIY creations. - Quality Electronic Kits, Electronic Projects, Electronic Schematics - An excellent educational blog for engineering students in providing great information on various electronics projects ideas, circuits, electronics tools, etc. from basic level to advanced level. - Free Electronic projects, schematics, diagramms, pcb, free electronic software and hobbilist electronics resources, electronic community. - Free verified electronics projects with schematic and circuit diagram with PCB layout and design in many circuits. Projects ranging from basic electronics. - over 1050 top electronics projects and electronic circuits with photos, datasheets and easy to read schematics plus how it works and how to build it. - Over 1000 Electronics Schematics. FM transmitters, audio and video, Hi-Fi and Hi-End, tube amplifiers, measured electronics and more.
Radio Frequency Circuits - so much designs, even EDI could not check them all - Very big database of electronic elements - Tutorials and kits for assembly of great diversity - Lots of schemes, mods and stuff for electric guitar pedals - Online calculator for coil and transformer properties. Gives values for inductance, Bmax, saturation current, and many more. - Electrical, design engineers & hi-tech lovers! Electronic Products features the ultimate in electronic information hot tips, trends, gizmos & gadgets.

Software and Downloads

LTspice - a very powerful and popular simulator. Can run on Windows and Linux systems
LTspice Yahoo Group - popular forum with lots of LTspice models and members to help you
RightMark Audio Analyzer - a very powerful and popular software for analyzing audio signal properties like THD, noise, spectrum, channel crosstalk with PC soundcard. For Windows systems, but runs on Ubuntu with Wine.
Electronic circuit design - EasyEDA - EasyEDA is a free and easy to use circuit design, circuit simulator and pcb design that runs in your web browser.
CadSoft EAGLE - PCB design software - even the free version has LTspice incorporation and auto routing. Windows and Linux distributions
potentiometer scale dwg Potentiometer scale in CAD format - This DWG file will help you to give your project more "professional" look. It contains different scales for potentiometer with a rotation of 270 degrees. You can open and edit it with free programs like DraftSight and A9CAD

These links are interesting ideas from independent sources. The author does not claim any responsibility for the information they contain.