Discrete Geometry Oberwolfach, Germany, April 10-16, 2005
Convex and Abstract Polytopes Banff International Research Station Canada, May 19 - May 21, 2005
Discrete Geometry Mainz Germany, June 16-19, 2005
Encuentros Españoles de Geometria Computational next at Santander, 27, 28 y 29 June 2005.
Inside the Cube: Algebra, Combinatorics, and Geometry Magdeburg Germany, July 01, 2005 - July 03, 2005
ADONET/CIM Geometric and Algebraic Approaches to Integer Programming Lisbon, July 11-15, 2005.
Summer School on Geometric Combinatorics University of Vienna July 18 - 29, 2005
IMA "Special" Workshop: Mixed-Integer Programming Minneapolis Minnesota, July 25-29, 2005
Algebraic and geometric combinatorics Crete Greece, 20-26 August, 2005.
Groebner Bases 2005: theoretical and practical effectivity Rikkyo University, Tokyo, Japan August 22--26, 2005
Optimization over Polynomials and Semidefinite Programming Klagenfurt Austria, Monday Sept. 12 to Friday Sept. 16, 2005.
Convex Sets and their Applications Banff International Research Station, March 4-9, 2006.
Workshop on Mixed Integer Programming June 5-8, 2006. At the School of Business on the University of Miami Campus, Coral Gables, Florida.
A session on ``Algebraic Techniques for Optimization part of SIAM conference on Discrete Mathematics, June 25--28 2006, University of Victoria, British Columbia.
ISMP_19th International Symposium on Mathematical Programming Rio de Janeiro, July 30-August 4, 2006.
Discrete Geometry: A satellite conference of the International Congress of Mathematicians Alcala de Henares, Spain, August 31-September 5 2006.
A year-long program: Applications of Algebraic Geometry IMA Univ. of Minnesota September 2006-June 2007.
Some other good canonical choices:
FoCM: Foundations of Computational Mathematics once every two years.
MEGA: Effective Methods in Algebraic Geometry, a biennial conference on computational aspects of Algebraic Geometry.
ANALCO: SIAM Workshop on Analytic Algorithmics and Combinatorics once a year
SOCG: ACM-Symposium on Computational Geometry Once a year.
SODA: (ACM-SIAM symposium on discrete algorithms) once a year.
ISSAC: International Symposium on Symbolic and Algebraic Computation (other conferences have the same initials). It runs once a year.
IPCO: Integer programming and Combinatorial Optimization Once a year (with exception of years when ISMP runs).
FPSAC: International Conference on Formal Power Series and Algebraic Combinatorics Once a year.
ICMS, International congress of Mathematical Software Every four years.