Large area coatings containing nanoparticulate metal oxides dispersed in polymers are manufactured at high speed (up to 200 m2 /min.) by curtain- or cascade coating on flexible substrates near room temperature. Simultaneously coated multilayers, which may contain different metal oxides, show interesting new properties for industrial applications. Thick (40 $m) coatings with rare-earth doped aluminum oxide nanoparticles have been commercialized for waterfast ink-jet media which are dry to touch after printing, show photo-parity and are very stable towards water, light and environment if appropriate inks are used. Strong capillary forces due to nanoporosity allow instant ink-absorption. Experimental techniques used to develop these materials and results related to imaging parameters are discussed. Thin layers (1-10 $m) of nanoparticulate, nanoporous TiO2 and LiMn2O4, dispersed in non-electroactive polymers such as polyethylene glycols, can be used as electrodes for rechargeable Li-ion batteries with very fast charge-discharge cycles and high power performance. The excellent ion-conducting properties of unsintered, nanoparticulate coatings of these metal oxides were unexpected and allow applications of temperature sensitive substrates and organic addenda. By coating very thin, almost or totally polymer-free layers of highly-porous, monodisperse aluminum-oxides with minimum particle size, display devices with improved optical efficiency were prepared. These layers have a low refractive index thus allowing for higher intensities of light emitted by organic electro-luminescers in OLED’s and PLED’s. This property is useful for mobile devices as phones and PDA’s. A hitherto unknown, photo-catalytic chemical reaction of the classical green emitter tris-(8-hydroxychinolino)-aluminum (Alq3) has been discovered in coatings of such optically efficient devices after exposing them to daylight in air. An efficient blue-emitting species of Alq3 with another stereochemical structure was directly formed within these layers at room temperature by photolysis in ambient atmosphere. Interesting new applications of specially designed, large-area coated and transparent nanostructured matrices on flexible substrates for optical gas sensors are discussed in more detail in this paper.