Surface Edit > Stitch > Shell Stitch Creates a special object called a shell from a group of surfaces, in preparation for Boolean operations or export to a CAD package.
Surface Edit > Rebuild Surface Recreates a surface with the same shape but different mathematical properties (for the purpose of simplifying it, or making it non-rational for export to a CAD package, for example).
Surface Edit > Claymate Integrates digitized clay model data with modeled surfaces, or offsets a group of surface while maintaining continuity between them.