OP... I think you need to be very careful when you say "no distortion." It means different things to different people. You can be sure that every lens available for a DSLR has some sort of distortion present - it's completely unavoidable when you design a lens.
For example, a rectilinear lens will make straight lines look like straight lines. This comes at the expense of stretching things at the sides and (especially) the corners of the frame. Lines are straight but things in the corner are stretched way out of proportion. In extreme cases, it can make some people look twice as tall as others.
The other extreme would be an equal-area projection. This is used in some fisheye lenses, and results in straight lines appearing curved but the relative scale of things is constant.
A lot of wide angle lenses try to go somewhere between the two extremes. This results in straight lines not being perfectly straight and some pincushion behavior by the lens.
Many of these effects can be corrected in post processing - Lightroom 3 and Photoshop CS5 or later have the ability.