Device concepts in semiconductor spintronics make long spin lifetimes desirable, and the requirements put on spin control by schemes of quantum information processing are even more demanding. Unfortunately, due to spin-orbit coupling electron spins in semiconductors are generically subject to rather fast decoherence. In two-dimensional quantum wells made of zinc-blende semiconductors, however, the spin-orbit interaction can be engineered in such a way that persistent spin structures with extraordinarily long spin lifetimes arise even in the presence of disorder and imperfections. We review experimental and theoretical developments on this subject both for n-doped and p-doped structures, and we discuss possible device applications.