Three more things I found while Twittering and using Google+.
Stay Connected to Your Broadband – an Improved ADSL Filter. I have a DSL line here, and have never had any RFI problems. In Great Britain, however, their broadband lines seem to be susceptible. This 2010 article shows you how to build a filter that will fix that right up.
Learn circuits and electronics from MIT. The Massachusetts Institute of Technology is putting a lot of courses online, and you can take them for free! This course, Circuits and Electronics, is the core course for all undergraduate electrical engineering (EE) and electrical engineering and computer science (EECS) students. Before you jump into this, realize that they say it will require about ten hours per week, and you need to know some basic calculus and linear algebra. This is an academic class, after all.
Open Hardware Journal. From the first page:
Open Hardware means sharing the design of physical or electronic objects with the public, similarly to Open Source software. The right to use, modify, redistribute, and manufacture, commercially or as a non-profit, is granted to everyone without any royalty or fee. Thus, Open Hardware designers hope to enrich society by developing a library of designs for useful objects that everyone can make, use, and improve.
The second issue features an article on the TAPR’s High-Performance Software-Defined Radio (HPSDR) project, which now includes over a dozen building blocks that can be used to assemble a high-grade 100 kHz to 55 MHz software-defined radio.