Creating a color palette when designing is an essential task. Here are a couple of resources I have been using that make this task a bit easier:
COLORLOVERS –> A great resource for various color palettes, patterns and shapes.
DEGRAEVE –> features a bunch of handy generators (a visual packing list generator, business card generator, a favicon generator and of course also a color generator). The color generator allows you to upload a bitmap and bam you got your index colors samples from the image.
COLORSCHEMEDESIGNER –> excellent website that allows you to explore various color combinations and then export them as html/css, or color palettes for Adobe Photoshop.
COLORSCHEMER –> same qualities, a little bit more advanced and polished + available for mobile devices and desktop.