Here are some great places for finding out more about the world of hardware and software tinkering
Schematics are the language of electronics, they provide a concise and comprehensive diagrammatic description of a circuit.
Schematics.com allows users to connect and share designs and ideas in a like-minded community.
A brilliant resource for those who want to build their own circuits.
General Raspberry Pi guides
The eLinux Raspberry Pi Hub is a wonderful resource for finding out more about what you can do with a Raspberry Pi.
Here you can find out about getting started with Raspberry Pi, available expansion boards, how the GPIO works and more.
eLinux.org also covers other boards and Linux in general.
Software tips and tricks
A great site for both how-to guides and explaining how to set things up so they work the way you want.
How-To Geek covers both beginner and more advanced topics, but it maintains an easy to read style throughout.
A great place to learn how to get the most from computers in general.
Project ideas for your Raspberry Pi
Full of project ideas and helpful hints this magazine makes a great companion to your Raspberry Pi tinkering.
Available both in print and free online it also contains reviews of add-ons and interviews with the community.
Ideal for when you want to find something new to do with your Raspberry Pi.
How to guides for making things
A great place to get instructions on how to make things or simply get some inspiration for your own projects.
Want to do something new with that Arduino for example, just search for Arduino, simple.
Finally you can share your projects with others so they can make their own as well, even better ^_^
Ever had trouble getting your webpage to look just right, struggling with CSS or page layouts?
With JSFiddle you can try snippets of your page and see what the final page looks like without editing your site
You can even save your fiddles for later, share them with others, and even work collaboratively with others.
The world of Linux
If you are looking for a great magazine for all things Linux look no further.
Content ranges from the latest things in the Linux world to advanced masterclasses.
Linux Voice sets itself apart by giving half of its profits back to the open source community, as well as making nine month old issues freely available (CC-BY-SA).
You can view a free sample issue here to get a feel for the magazine.
Web based circuit simulator
Online Circuit Simulator with SPICE
PartSim is a free and easy to use circuit simulator that runs in your web browser
It provides AC/DC/Transient simulation and easy to use graphical output of probes
It also has a good range of vendor parts for you to quickly get up and running
Circuit design and layout
PCBWeb is a free CAD application for designing and manufacturing electronics hardware.
For those who wish to get into making their own circuit boards this is a great place to start.
This program lets you design the circuit, layout the board, and even helps get your new PCB ordered.
Currently only Windows is supported, but Mac and Linux support is planned.