Aabel http://www.gigawiz.com/
Statistical and Graphing Software for Mac OS X. Site provides screenshots and features list, together with pricing details and online ordering facility.
MultyGraphiX http://multygraphix.gracebyte.com/
Generate 2D and 3D plots of explicit and parametric functions, in various coordinate systems. Site provides screenshots, features list, and alows download of an evaluation copy.
DeadLine http://deadline.3x.ro
Free windows software performing graph plotting and root-finding for algebraic functions. Site includes a features list and tutorial.
Plot 3D http://www.plot3d.net/
2D and 3D function graphing. Includes freeware download, and a gallery of output. [Windows 98-XP]