If I were your i'd consider either political science/international relations or mathematics or a minor in both. Most graduate programs in business require substnatial mathametics background. If your in the lesat bit interested in doing graduate level economics mathematics is essential. If your interested in going into finance, or even certain branches of accounting, business management math is requirement. It would be useful to take a programming class or two but particularly one on either mathemtical computation or one that teaches you to program on a common statistical package.
I.R/Political science is another option only if your interested in going to work in the government as a policy analyst. Having a background in this field particularly political economy, public policy courses will allow you to consider entering public policy school something that helps with landing higher level beuracratic positions.
Regardless of what you do I would plan on taking some math and additional statistics (unless your school offers undergraduate econometrics). Taking a couse in Probability, Linear Algebra, Multivariable Calculus (Calclus III), Regression Analysis, is probably the most useful things you could do in your undergraduate. Especially since common career routes for economics students tend to be in banking or finance. Statistics and probability are particularly useful. Linear algebra is the language of stats.
If you do a math minor I'd try to also take a course in stochastic processes, differential equations I & II, and a proofs based mathematics course. Top programs like that proof based course to be real analysis, but its a very difficult course.
The routes I just outlined are routes you can take if your interested in working in something related to economics,
in careers such as a economic consultant, policy analyst, or economist. Most of these careers will require you to probably take a masters degree of some sort.
You could do a compsci minor, but the direction your going is more like economics as a liberal arts degree. Then what you wind up doing later in life will probably quite unrelated to your field and its really hard to say what you will do with it. (not that you won't do something). The one thing to understand about undergrad degrees is they generally aren't meant to get you on a particular career track. The exception to that statement is if you do a degree in the applied sciences (engineering/compsci), or business (accouting, marketing, MIS, Finance). Most programs undergraduate are general and the only way you'll windup in some particular field is with what you do outside of school (relavent work experience, networking) or getting further education to get into a field ( for example teaching, nursing, pharmacy, finance, acounting are fields that can be entered with any degree+ a certification of some sort. Sometimes particular degrees are more suited towards a particular certifaction (actuarial candidates tend to be math majors, CFA candidates are usually economics, math or statistics).