Superalgebras have been used in various questions of algebra in a very striking way. To give some instances:
Kemer's proof of the fact that, over a field of zero characteristic, every system of identities expressible in terms of the product in associative algebra follows from finitely many of them (Finite basis property of identities of associative algebras).
Nilpotence results by various authors, see, for instance, Zel'manov'sZelmanov's celebrated proof of global nilpotence of Engel Lie algebras (Engelian Lie algebras), or the survey of Vaughan-Lee indicating some other directions (Superalgebras and Dimensions of Algebras).
Shestakov's elegant examples and counterexamples in different varieties of nonassociative algebras (Superalgebras and counterexamples).