  We show that refined Chern-Simons theory and large N duality can be used to
study the refined topological string with and without branes. We derive the
refined topological vertex of hep-th/0701156 and hep-th/0502061 from a link
invariant of the refined SU(N) Chern-Simons theory on S^3, at infinite N.
Quiver-like Chern-Simons theories, arising from Calabi-Yau manifolds with
branes wrapped on several minimal S^3's, give a dual description of a large
class of toric Calabi-Yau. We use this to derive the refined topological string
amplitudes on a toric Calabi-Yau containing a shrinking P^2 surface. The result
is suggestive of the refined topological vertex formalism for arbitrary toric
Calabi-Yau manifolds in terms of a pair of vertices and a choice of a Morse
flow on the toric graph, determining the vertex decomposition. The dependence
on the flow is reminiscent of the approach to the refined topological string in
upcoming work of Nekrasov and Okounkov. As a byproduct, we show that large N
duality of the refined topological string explains the ``mirror symmetry`` of
the refined colored HOMFLY invariants of knots.
