This paper presents scalable solutions for achieving virtual humans able to manipulate objects in interactive virtual environments. The scalability trades computational time with the ability of addressing increasingly difficult constraints. In time-critical environments, arm motions are computed in few milliseconds using fast analytical Inverse Kinematics. For other types of applications where collision-free motions are required, a randomized motion planner capable of generating motions of average complexity in about a second of computation time is employed. The steps required for defining and computing different types of manipulations are described in this paper.