Full VEX deformer framework is available on Orbolt:
Bend, Bias, Boxify, Cylindrify, Flatten, Melt, Mountain*, Ripple*, Skew, Spherify, Stretch, Taper, Twist, Vortex, Wave
These are the set of deformers I wrote for Houdini 12. Designed to be fast, generic, uniform, procedural, versatile, reusable, intuitive and extensible. They are all written in VEX which is extremely fast.
Each of them is defined using a single generic VEX function that's context-agnostic, encapsulated into VOPs, which make up the core lower-level part of the system. SOP deformers use these operators internally to provide high- level access to the same deformers.
Generally you would use the SOP deformers, but use the VOP versions when you need lower-level control, or to manually combine results with other VOPs, or if you need to deform anything other than point positions, etc. You can also use the same VEX functions used by the VOP deformers in your own code if you prefer writing VEX.
* Original code by Side Effects Software