Well, for someone with tastes and understanding of functions like myself, I'd recommend a Canon 5D, 40D, or 1Ds Mark III.
For a beginner photographer, I'd recommend the Canon Digital Rebel XT, XTi, or XSi.
I haven't shot with Nikon in a year or more, so I really couldn't make any suggestions in that field. As I said, use what is most comfortable for you; don't get too caught up in what others are using, or whats the "latest and greatest".