It's hard to list all the possibilities that are open to you if you combine your math courses with computer-oriented studies. You may find a job in any field that requires managing large collections of data; you might also design computer systems themselves, prepare the internal software to operate them, or program solutions to engineering or business problems. It can't hurt to learn more than one computer language, simply to show a potential employer your capacity and interest in learning.
Here are some courses at OSU that will complement your knowledge of computer science:
MATH 3653 Discrete Math II (computers)MATH 4013 Calculus of Several Variables
MATH 4223 Intermediate Differential Equations
MATH 4283 Complex Variables (electrical engineering)
MATH 4513 Numerical Analysis
MATH 4583 Intro to Math Modeling
MATH 4663 Combinatorial Math (computers and problem solving)
Two specific emphases possible are Scientific Computing and Computational and Applied Analysis.