I have around $300 to spend on a new digital camera. My current one is very crappy and grainy. I'm a very amateur photographer, but I'd like to get a camera that can take close ups (a macro lens?) and decent night pictures, neither of which my current camera can do very well.

Always buy a canon. They are the best. The best value for money. Its not all about pixels either. Before the days of digital cameras, my motto was, always buy a Nikon. My camera cost me about AUD$400. You can see the results on my blog, a $300 version shouldn't be too much worse than that. Next time i buy a camera, I will go for an expensive SLR, but that will be because I want better lens quality. They say its cheaper to buy your camera online. So look around for the best model you can get for the money. If you are unsure about models, look for a shop that helps professionals and also sells to amateurs. They usually know what they are talking about when it comes to what model to get.