Modern marketing is all about data. Forecasts, ROIs, opportunities and revenues are solely sales metrics. Marketing become data-driven and you need tools to derive and evaluate this data.
SEO takes pretty good chunk of the marketing budget and have to be accurately estimated. However, the ROI for SEO is very hard to predict. There are not that many tools out there that can help you with calculating SEO potential but here are some that are very helpful.
Via Frédéric DEBAILLEUL, Pharmacomptoir / Corinne Thuderoz