Addressing moisture in a basement, to improve building robustness and avoid that musty "basement smell," involves eliminating intrustion of water from outside. Water may be coming in via leaks in the wall or floor due to cracks in the concrete, diffusion through the relatively porous concrete, or it may be simply a matter of exterior humid summer air contacting uninsulated walls that are in contact with cool ground. The ground is apt to remain in the 50s through the summer, while the dew point of summer air typically is above that.
Coating the interior concrete surfaces with a product that seals cracks against leakage and also seals the porous concrete against diffusion can go a long way toward reducing those two sources of moisture.
When contemplating the use of an exhaust fan to remove moist air from the basement, remember that the air removed will be replaced with air leaking into the basement, from either the living space above or the outside. If that replacement air is not dry, then ventilating the basement is a waste of time. Once any leaks via cracks have been eliminated and the surface sealed against diffusion, the next step is to insulate the walls with rigid or spray-applied foam, and finally covering that foam with something like sheetrock for ignition and thermal protection of the foam. The insulation will keep the inside surface above the dew point of the air. The insulation also will make the basement notably warmer in winter and reduce greatly what often is a huge parasitic heat loss to the ground.
For more reading on this, here are a few links:
http://www.greenbuildingadvisor.com/...-basement-wall
http://www.finehomebuilding.com/desi...-basement.aspx
http://www.greenbuildingadvisor.com/...g-wet-basement