Lua - 240 characters
Note: Prints 1.#INF and -1.#INF instead of NaN.
a,b,c=...o="+-*/"f=function(...)g=table.concat({...})loadstring('x='..g)()print(g..' = '..math.floor(x+.5))end for d in o:gmatch(".")do for e in o:gmatch(".")do f(a,d,b,e,c)f(a,d,c,e,b)f(b,d,a,e,c)f(b,d,c,e,a)f(c,d,a,e,b)f(c,d,b,e,a)end end
Output
5+0+13 = 18
5+13+0 = 18
0+5+13 = 18
0+13+5 = 18
13+5+0 = 18
13+0+5 = 18
5+0-13 = -8
5+13-0 = 18
0+5-13 = -8
0+13-5 = 8
13+5-0 = 18
13+0-5 = 8
5+0*13 = 5
5+13*0 = 5
0+5*13 = 65
0+13*5 = 65
13+5*0 = 13
13+0*5 = 13
5+0/13 = 5
5+13/0 = 1.#INF
0+5/13 = 0
0+13/5 = 3
13+5/0 = 1.#INF
13+0/5 = 13
5-0+13 = 18
5-13+0 = -8
0-5+13 = 8
0-13+5 = -8
13-5+0 = 8
13-0+5 = 18
5-0-13 = -8
5-13-0 = -8
0-5-13 = -18
0-13-5 = -18
13-5-0 = 8
13-0-5 = 8
5-0*13 = 5
5-13*0 = 5
0-5*13 = -65
0-13*5 = -65
13-5*0 = 13
13-0*5 = 13
5-0/13 = 5
5-13/0 = -1.#INF
0-5/13 = 0
0-13/5 = -3
13-5/0 = -1.#INF
13-0/5 = 13
5*0+13 = 13
5*13+0 = 65
0*5+13 = 13
0*13+5 = 5
13*5+0 = 65
13*0+5 = 5
5*0-13 = -13
5*13-0 = 65
0*5-13 = -13
0*13-5 = -5
13*5-0 = 65
13*0-5 = -5
5*0*13 = 0
5*13*0 = 0
0*5*13 = 0
0*13*5 = 0
13*5*0 = 0
13*0*5 = 0
5*0/13 = 0
5*13/0 = 1.#INF
0*5/13 = 0
0*13/5 = 0
13*5/0 = 1.#INF
13*0/5 = 0
5/0+13 = 1.#INF
5/13+0 = 0
0/5+13 = 13
0/13+5 = 5
13/5+0 = 3
13/0+5 = 1.#INF
5/0-13 = 1.#INF
5/13-0 = 0
0/5-13 = -13
0/13-5 = -5
13/5-0 = 3
13/0-5 = 1.#INF
5/0*13 = 1.#INF
5/13*0 = 0
0/5*13 = 0
0/13*5 = 0
13/5*0 = 0
13/0*5 = 1.#INF
5/0/13 = 1.#INF
5/13/0 = 1.#INF
0/5/13 = 0
0/13/5 = 0
13/5/0 = 1.#INF
13/0/5 = 1.#INF
