SaaS METRIC OF THE WEEK: Product Market Fit
Andrew Chen from a16z is excellent, and his PDF/deck on going from zero to Product Market Fit is awesome (For SaaS, he calls this a 5% conversion rate from free-to-paid, or 3X CPA to LTV ratio, or less than 2% monthly churn rate, or TL;DR.... just a clear path to $100k MRR). He also has an accompanying article with notes.