The introduction of an aminoethyl side chain into cyclopentadienyl compounds of many d-block elements leads to interesting changes in structure and reactivity compared to the parent species: (i) A hemilabile bonding situation is observed in complexes with low-valent transition-metal centers; (ii) amino-group coordination to an adjacent metal or nonmetal center creates novel types of bimetallic compounds; (iii) complexes with a tethered ammoniumethyl group often show good solubility in protic solvents, relevant with regard to organometallic chemistry in water. These features together with others are described in this review, which informs about the synthesis and properties of this new type of transition-metal complexes.