Online resources about electronics
Here is a laundry list of online learning resources about electronics.
Lessons In Electric Circuits (which All About Circuits is derived from)
MIT OpenCourseWare 6.002 Circuits and Electronics (Fall 2000)
Bob Pease Analog Engineer and thinker from National Semi
Op Amp Applications by Walter Jung is either available in print (2005 ed) or as a free download (2003 ed).
A Designer's Guide to Instrumentation Amplifiers from Analog Devices by Charles Kitchin and Lew Counts
Basic Analog for Digital Designers (Intersil AN 9510 PDF)
An audio circuit collection, Part 1 (TI)
Op Amps for Everyone Design Guide from TI
Understanding Basic Analog - Ideal Op Amps - Several examples of amp circuits are described.
Single-Supply Op Amp Design Techniques
Analog Electronic Design in a Day! free online course from TI
SwitcherCAD / LTspice III - a free full featured SPICE program from Linear Technology
Eric KE6US has a page about SPICE for Hams (radio amateurs).