Wouldn't duplicating the verticies defeat the purpose of using vertex arrays (re-using already stored verticies)?
I'm a newbie, so maybe I just don't get it:)
What does everyone else do?
Since you need several texCoord, your only option is using several vertices. (Multitexturing won't help you here - at least not performance-wise - since then, you are applying all six textures to all faces).
If you don't use lighting, the vertex-processing part is very small anyway and if you use lighting, you would need several normals per vertex as well (one for each face the vertex is part of), if you want to keep the edges and not have something that has the outline of a box but the shading of a very weird sphere.
The reuse only makes sense, if the vertices don't mark hard edges but rather support a curved surface (NOT in the NURBS meaning) or if you want to tesselate a plane in order to get better specular hightlight.
Concerning HamsterofDeath's suggestions, yep you could just use one single texture for all faces, where you set up your texture-coordinate up accordingly. This is what you would for example do with more complex models anyway, you don't have a texture for every face. The only drawback is of course, that your texture-resolution is more limited, but unless you want your cube to fill almost the entire screen, no problem there.