[plt-scheme] Good intro to Scheme macros?

It's not exactly what you're looking for, but you or others may want
to look at the macros notes at

  http://www.cs.brown.edu/courses/cs173/2003/Textbook/

# 2003-11-17: Domain-Specific Languages: An Example
# 2003-11-19: Implementing a DSL Compiler: Introduction to Macros
# 2003-11-21: Macros and their Impact on Language Design

At some point I hope to expand it to explain things like hygiene
better, but not in the immediate future.

There is a famous set of notes on macrology that used to be posted on
c.l.scheme.  I wouldn't know where to find it.

Shriram