Yeah, I pretty much agree with Michael's equipment list. It should be noted, though, that there are a lot of photogs who work exclusively with natural light, as I do 98% of the time. Works just great, as long as you know how to use the light you're dealt.

For the situations where I absolutely have to use it, I have a White Lightning monolight with a huge softliter (60") that I use to mimic windowlight. I think I used it twice last year. Either way, you'll HAVE to have a handheld meter. Besides your camera and lenses, it's the most important piece of equipment you can buy IMO.