Accelerated ionized cluster beams are used for surface nanostructuring of bulk diamond, chemically vapor deposited (CVD) diamond films, single-crystalline silicon, or glass, among others. Beams of CO2 clusters with about 1000 molecules per unit charge are accelerated to up to 120 keV kinetic energy for mask projective surface bombardment. Patterning is achieved via physical as well as chemical surface erosion. Very smooth eroded surfaces result for bulk natural diamond, silicon, and glass. Polycrystalline, strongly faceted CVD diamond films are effectively planarized. Submicrometer structures with adjustable wall inclinations can be generated. Atomic force microscopy of isolated impact structures reveals hillocks instead of craters. The collective motion of the impacted surface material is considered crucial for the cluster impact induced nanomodifications.