In 1911, Schur defined the $Q$-Schur functions. The $Q$-Schur functions are important in several different contexts including the representation theory of Lie superalgebras, and certain cohomology classes. The peak algebra is a generalization of the Hopf algebra of $Q$-Schur functions that was introduced by Stembridge using enriched $P$-partitions. In this talk, we extend the notion of peak algebras to shuffle, tensor, and symmetric algebras. This talk is based on joint work with Shu Xiao Li and Nat Thiem.