uC Hobby – A new and growing resource center for microcontrollers (they emphasize ARM7) and related digital electronics topics. Along with the blog for general ARM7 projects, they have links to several other solid project blogs and a set of how-to’s. I recommend checking out the surface mount soldering one with the $40 Home Depot heat gun, which I just bought recently.
For JTAG Wiggler information, see the dedicated page.
AVR
AVR Freaks. An established community with forums and a project database. Responses on the forums come pretty fast. Also includes a large parametric table of available AVR microcontrollers, and a database of retailers for chips, development boards, etc.
This is Circuit Simulator written in Java. It runs as an applet. This is a great program, and I highly recommend it- even if you’re just messing around. It supports many components, and also has a few popular logic chips. More importantly, you can insert virtual probes and observe the circuit in a virtual oscilloscope. There are a bunch of prebuilt circuits in the menu, in case you’re lazy.
Digital Electronics Resources
Here is a compiled list of resources for digital electronics. I will be adding as often as possible to this list:
ARM Microcontrollers
AVR
Misc. Digital Electronics