Java implementation DrawSWF is freeware. It outputs both SWF and the SVG formats. As ver 1.2.7 it is stable, requires the Java engine be installed (JS2E 1.4.2 here), and looks like it will become powerful and useful around version 5.

Of course there's Swish, but there is also Koolmoves and Selteco Flash Designer - each at $39.95.