I saw Dave McClure give a talk at FOWA 2009 with these slides: http://www.slideshare.net/dmc500hats/startup-metrics-for-pirates-long-version http://www.slidesh

I saw Dave McClure give a talk at FOWA 2009 with these slides: http://www.slideshare.net/dmc500hats/startup-metrics-for-pirates-long-version http://www.slideshare.net/dmc500hats/startup-metrics-for-pir... He takes an even more brutal approach to customer development: you should remove features until your customers scream at you! This might be a bit too severe but I think that it summarises the core philosophy behind customer development pretty well.