@jdailey - If you search for an option to individually customize sidebars on pages and posts in a comfortable way try plugin 'Widget Wrangler'. On the edit page it displays drop zones for each sidebar and a list of all available widgets. Simply drag a widget on a drop zone and save the post. With the words of @Chip Bennett this is like configuring the widget areas directly on the edit page. Currently the biggest disadvantage is the necessity to clone the widgets from the WP widget system, what may fail in some cases. I would very much appreciate to see WP widgets going in such a direction. Meanwhile I don't use the WP widget system any more.

@Donna Fontenot - A replacement for the text widget with the tinymce editor already exists. See plugin 'Spots'.