a free user interface builder for GTK+ and GNOME interfaces designed are saved as XML, and by using the libglade library these can be loaded by applications dynamically as needed. (Glade can also generate C code)
Guy Steele's keynote at the 1998 ACM OOPSLA conference on "Growing a Language" (mostly about JAVA) discusses the importance of and issues associated with designing a programming language that can be grown by its users.
S. Pyysalo, F. Ginter, K. Haverinen, J. Heimonen, T. Salakoski, and V. Laippala. Proceedings of the Workshop on BioNLP 2007: Biological, Translational, and Clinical Language Processing, page 25--32. Stroudsburg, PA, USA, Association for Computational Linguistics, (2007)
M. Adams, and R. Dybvig. ICFP '08: Proceeding of the 13th ACM SIGPLAN international conference on Functional programming, page 179--188. New York, NY, USA, ACM, (2008)
A. Bogoni, W. Xiaoxia, I. Fazal, and A. Willner. Optical Fiber Communication - incudes post deadline papers, 2009.
OFC 2009. Conference on, page 1-3--. (2009)