As grid infrastructures mature, an increasing challenge is to provide end-user scientists with intuitive interfaces to computational services, data management capabilities, and visualization tools. One novel approach, being successfully applied in the domain of Computational Chemistry, is to leverage the capabilities of the Mozilla framework to provide rich end-user tools that seamlessly integrate with remote resources such as web/grid services and data repositories. The Mozilla framework provides much of the infrastructure to build rich end-user applications, but lacks the capability to integrate with Grid protocols and APIs. In this paper we present the design and evaluation of Topaz, a Mozilla-based component that provides GridFTP functionality to the popular Firefox browser. Topaz provides end-user scientists with a familiar and user-friendly interface with which to access arbitrary GridFTP servers by providing upload and download functionalities as well as by obtaining and managi...