I like patio11's approach and agree we should write our own business systems to meet our particular need - I am finishing off a CMS that I have also opensourced (it's text and templates and cookies for tracking, about 100 lines)
Now I am not promoting that codebase, only releasing it cos I don't want to waste a GitHub private repo. But I do wonder if we should all write our own CMS / mailchimp / an tester or if we should community build them or just roll up packages
Partly I am asking what are the common functions we should all have a custom builds and partly where do we draw the line on build vs "buy"