Topology plots
Espript will produce nice Postscript plots from aligned sequences, highlighting secondary structure: http://espript.ibcp.fr . Roman Laskowski's program PDBSUM seems to fulfill a similar purpose.
Pro-origami: http://munk.csse.unimelb.edu.au/pro-origami/
There is also a program called TOPS which I understand can be obtained from David Westhead's group in Leeds, email D.R.Westhead@leeds.ac.uk
CCP4's Topdraw is a drawing tool to help you make your own topology drawing.