I have been a proud Nikon user since my dad gave me my first camera at age 9. I witnessed the evolution of film to digital. At every step Nikon has produced high quality gear that, as a professional has never once let me down. Here are a few items I could not live without.
Nikon 24-70mm | 2.8 ED lens

This lens is phenomenal. It has been my new work horse ever since I purchased it in December 2007. It is very sharp even at the edges. The 24-70mm range is very effective for shooting weddings. Typically when I am in the field I have this lens, an 80-200mm 2.8, and a 16mm 2.8 fisheye. I would say the 24-70mm gets the most use out of the 3 lenses. It is fast, sharp, tough and dependable. I would not recommend trying this at home but I even dropped mine and it still works great! It has a little ding on it, but I tested it out thoroughly since then and it continues to be dead-on. Kudos Nikon.
D3

I love, love, love this camera. The white balance is phenomenal. I shoot it on either auto or sometimes tungsten and get wonderful accurate results. The LCD screen is bad ass. It is huge and better yet very accurate. I hardly look at a histogram anymore. The full frame CMOS chip provides files with an incredible dynamic range. It is also incredibly fast! There is no lag time even in low light. This camera is a joy to shoot. It almost makes it like cheating! Nikon enabled photographers to get back to pushing the art of their medium rather than struggling with the confines of the medium. I can only imagine what the D3X will produce. The low light capabilities of the D3 have totally changed the ways images are captured. At least I know that is the case with me. We now use shots photographed at ISO 6400 in our wedding albums on a regular basis. This allows us to capture REAL moments with available light that would otherwise go undocumented or be washed out with flash thereby destroying the intimacy of the moment. Mark my words this camera will change the face of photography forever.
D700

This camera is insane. Basically, it is a D3 in a smaller package. It has the same large 3″ LCD and full frame CMOS chip as its big brother, but it is considerably lighter. This can be very significant when shooting a 12 hour wedding. It is a 12 megapixel FX format camera and has an ISO of up to 6400. This baby packs a powerful low light punch. Even at the higher ISO it still has minimal noise and really works great at the reception. Our assistant currently shoots this camera at all of our events and in a few advanced lighting situations, it has surpassed expectation.