I'm writing an intermediate 6502 tutorial for commuters. It's for JBit, but it only uses the console (10x4 memory mapped char matrix + numeric keypad) and has a well-defined hardware abstraction layer, so it might have a general appeal. The tutorial assumes some basic knowledge of the 6502 and shows how to write a complete application from scratch. The application is a simulation of a digital clock, is a bit less than 1K and is ROMable. You can try the resulting application here (Applet): http://jbit.sourceforge.net/demo/sheets_e1.html. I've split the code in 8 parts and I've written about 30% of the tutorial. You can download the first part here:

http://jbit.sourceforge.net/doc/JBit-E1.pdf

I prefer to release the tutorial incrementally, but I won't be bothering you with posts about the updates. My guess would be that I should be able to upload an additional part every week (same URL).