I put the equipment in an order as to what I think are most important. Lets run down the list.
1 Obviously the camera is the most important thing. I have a Nikon D3000 and what you most recently see on this blog is mostly the product of that.
2 Most would not agree, but a tripod is so important to have especially when you are shooting in low light and with a low shutter speed and aperture. Basically any tripod is good to have (don't really have a favorite brand), just make sure it can be adjusted in various ways and note how high it goes.
3 The lenses that you have are very important as well. The standard lens that come with the Nikon D3000 is good, but to adventure into other territory, you may want to consider getting a macro/micro lens for close detail, a wide angle lens for landscapes, and a telephoto lens for far away objects. Amazon sells a lot of these for great prices.
4 Next on our list is an external flash. This is much more powerful than the built in flash on Nikon's models. You can also diffuse the light through a variety of ways. Also on most Nikon models, you can actually use the flash wirelessly and not even have it attached to the camera!
5 Umbrella lighting is also a good source of external lighting. It is really good for studio photography like family portraits. These lights will also flash wirelessly with most Nikon models.
All images are from Google Images.