Northwestern Institute on Complex Systems Conference
http://www.northwestern.edu/nico/complexity-conference/

International Conference on Complex Systems (ICCS 2007)
http://necsi.org/events/iccs7/
Boston: 10/28/07 to 11/207 - Submission dealine 5/31/07

IEEE Meeting on Computational Complexity
http://facweb.cs.depaul.edu/jrogers/complexity/
San Diego: June 2007

UCLA - Human Complex Systems Conference
http://hcs.ucla.edu/arrowhead.htm
Lake Arrowhead: 2007 meeting already held, not sure about 2008 meeting

Center for Nonlinear Studies (Argonne) Conference
http://cnls.lanl.gov/annual27/
2007 Conference already held, not sure about 2008 meeting