Exec roles have been satisfying, but still enjoy building things.
Inventor and patent-estate/i.p. management (My issued and published patents here: http://is.gd/ErvSd2 )
I think, as a rule, it's tough to manage others well if you don't know how to do (and actually do) what they do.
• R, MATLAB, SAS, BUGS, Weka, MapReduce/Hadoop, Python, Java, SQL, other programming languages;
• Statistics (frequentist and Bayesian);
• Predictive modeling (logistic regression, linear regression, ...);
• Machine-learning (boosting, bagging, Random Forest, neural networks, ...);
• Text mining & unstructured data analytics (LSA, sentiment analysis);
• Ontology management and automapping (OWL, ...