Do you have old images in Aperture that turn bright green when you reprocess them with the new RAW decoder in Aperture 3? This article tells you how to fix this and get your photos looking like they should!
You should know exactly what equipment you have with you whenever you're shooting...
That's because they're probably stored on a drive that is OFFLINE.
Your lens came with a hood for a reason. Use it.
Do you have a RAW file whose thumbnail doesn't match the actual image?