This paper proposes algorithms for computing extent measures and approximate representations of a stream of points in R² or R³. In particular, we study the problems of computing various extent measures (for example diameter, width, smallest enclosing rectangle, and smallest enclosing disk) and of approximating a set of points by a circle or a line. We show that these problems can be solved efficiently using graphics hardware even in the streaming model. (P. Agarwal, S. Krishnan, N. Mustafa and S. Venkatasubramanian. Streaming Geometric Optimization Using Graphics Hardware. Proc. 11th European Symposium on Algorithms, Sep 2003.)