Dr. Fabrice Jossinet from the University of Strasbourg recently released Assemble2, a Chimera plugin for designing RNA structures in 2D and then generating the corresponding 3D structure.  If you're an RNA person, maybe you'd like to try it out and offer feedback.  Here's the Assemble2 web site:

--Eric

                        Eric Pettersen

                        UCSF Computer Graphics Lab

                        http://www.cgl.ucsf.edu