Amphiphilic peptides can be programmed to yield functional self-assembled structures at interfaces and in bulk. In particular, β-sheet structure provides a simple platform with periodic alternation of hydrophobic and hydrophilic amino acids that tends to form fibrilar structures in solution and monomolecular coatings at interfaces. Designed amphiphilic β-sheet peptides, their structures and a few of their potential applications will be presented including: calcium-phosphate mineralization induced by amphiphilic and anionic hydrogels, Phe-X-Phe tripeptide hydrogels enabling facile templating of crystalline silver nanorods. A few other systems will also be briefly introduced: peptide coatings to titanium-oxide surfaces, sensing of an organophosphate by peptide monolayers and nanoparticles formation for intracellular drug delivery.