Raw v's JPEG
I often get asked what RAW is and why would you wanna shoot RAW. Well, RAW is what it says, its the image that the sensor saw, un-altered in anyway, thats left for you to do in post processing. Generally I post process (via Apple Aperture or Adobe Lightroom, though I prefer Apple Aperture) all of my photos that make it to my flickr account, but I shoot JPEG+RAW, i.e. the camera saves a RAW file and a JPEG file for me for each shot I take.