Many interesting combinatorial problems - graph coloring, maximal matching, set cover, and knapsack among others - can be reformulated as integer linear programs. One thing that all of these reformulations have in common is that they are so called 0-1 integer programs. That is, the variables in the program recieve values in $\{0,1\}$.
I'm preparing for a class I'm teaching on linear programming, and so I'd like to give a variety of interesting examples of integer programming.
My question is: Is there an interesing combinatorial problem that can be restated as an integer linear program where the values of the variables are not necessarily 0-1?