Speedlight/Flashes for a Nikon D90?

So I've been researching the D90 for a while because I want it for my birthday. The one I'm looking at on the Nikon website includes the lens so that wouldn't be a problem. But should I also ask for the above? I've been in classes where they say it's good to have, but could I turn out shots just as well without out? I'm somewhat of a beginner in that I'm not entirely sure what it does… Enlighten me?

Unless you plan on doing a lot of event photography, you may not really need an external flash.

If you do plan on using flash a lot, then the SB 600 would be the most economical choice.

I purchased a d90 kit in early fall, and it worth every single penny. I suggest that you play around with your D90 for awhile before you go straight into buying a speedlight. I feel that it would be too difficult to try and learn the controls of your mid-level SLR as well as a speedlight, at the same time; especially as a beginner. Also, it depends on what type of photography you want to specialize in. If you're in to doing portraits, then a speedlight is necessary, however if you're in to landscapes and nature, you may not need one at all. If you do decide on purchasing a speedlight, you should start with the SB-600, because it is a notch above the simplistic SB-400, and produces great results.

It gives you the amounnt of light where you want and when you want. Simple as that. If you don't want that you don't want a flash