I agree with everything above.

Let me add that Scott's modules are perfectly localisable, a concern for us in non english speaking countries.

The 'publish often' strategy is also very cool. I can bring my customers a little more at any time, by just upgrading a module. They like to get a little -or big - extra feature on a regular basis.

The templating mechanisms in most modules is extremely flexible. I can satisfy my clients' requests so precisely, that they believe I wrote the code !