A fiber velvet comprising nano-size fibers or nanofibrils attached to micro-size fibers is disclosed. Methods of manufacturing the velvet as well as various uses of the velvet are also described. For example, the fiber velvet can be used as a thermal interface or as an adhesive material. The nanofibrils may be attached to a flat base or membrane, or may be attached to the tip portions of the micro-size or larger diameter fibers. Various attributes of the micro-size fibers and of the nano-size fibers, for example, geometry (e.g. size, length, packing density) material type (e.g. carbon, metal, polymer, or ceramic) and properties (e.g. conductivity, modulus, surface energy, dielectric constant, surface roughness) can be selected depending on the desired attributes of the fiber velvet. The nanofibrils have a diameter of less than about 1 micron, and may advantageously be formed from single walled and/or multi-walled carbon nanotubes.