khovanov homology is a knot invariant, which generalizes and more specifically categorifies the jones polynomial of knots. however, in the construction of khovanov homology we seem to make several choices in the frobenius algebra that we consider. in this talk, we will discuss a distinct alternative to khovanov homology known as lee theory, in which we make different choices on our frobenius algebra. these different choices break the q-grading, but allow us to create a filtration, and use this to define a rasmussen's s-invariant. we will describe several properties and applications of this invariant.