Dim Pro has some limited but useful Hammond patches if you only need something generic. But if you're looking for a virtual instrument that nails the full range of the Hammond/Leslie sounds, then VB3 is your solution. At fifty bucks, it's quite affordable and surprisingly authentic. I've even used it live on stage, and all my synth controls mapped to it nicely.
VB3 is the engine under the hood of what is arguably the best Hammond clone on the market, the Crumar Mojo: