New methods for modifying graphitic carbon surfaces without electrochemical assistance, and without the deliberate formation of carbon surface oxygen functionalities, have emerged in the past decade. The approaches rely on spontaneous reactions of aryldiazonium salts, primary amines, ammonia and iodine azide at room temperature, chemical reduction of aryldiazonium salts, reactions of alkenes and alkynes at elevated temperatures and photochemical reactions of alkenes, alkynes, azides and diazirines. This review describes the methodology and scope of these reactions at graphitic carbon materials (excluding carbon nanotubes) and examines mechanistic possibilities and future prospects.