Choose (1) or (2):

(1) If you want this board to tell you that you should buy a new body or lens:

Yes, you should buy a new body and lenses. I think you could greatly improve every aspect of your photography by purchasing a D300 or D700, and a select group of Nikkor f2.8 VR lenses. They will make a world of difference.

(2) If you want to hear the truth:

Only you can answer this question. You need to look over the last two years of photography and see where your gear has limited you. What do you want to do that you have not been able to do? What within your images do you wish you had more or less of? What challenges did you have on location, in controlling your camera, light, composition? Only by doing this can you really understand what it is that you need to replace if anything.

So for example: you mention that you have a crappy tripod. In what way is it crappy? Is this because it is brand x and everyone knows brand x is cheap? Or is there some issue in setup or teardown, or perhaps it isn't stable enough with a particular lens, or maybe it falls over in lightest breeze. If you had, say a top of the line Gitzo + RRS ball head, how would that change your photography?

Perhaps you wish to go shoot birds, and you don't have enough length at 200mm, or perhaps the converter makes things too soft. This might mean its time to look at longer lenses.

Perhaps you have lots of portraits and they are not as tack sharp, or your 50mm is too short...then perhaps a 85mm would be good. Or maybe you find that you are not getting fast enough frames per second and missing some good action shots on the soccer field, or maybe the keeper rate in fast focusing situations like sports is really poor. Maybe you should consider a new body...

You get the idea. Only by understanding your needs and challenges can you really understand whether you need a body or lens or maybe nothing at all. So, look over your images, evaluate the focal lengths, issues and concerns. Then search this site for specific questions regarding your issues, or ask new questions if they have not been asked before.

Oh and yeah, buying new gear is fun, I get that. But it tends to be a bit pricey, and heck, studying and researching this stuff is fun too.