Luke Wroblewski wrote an article for Boxes and Arrows about using colors found in nature as inspiration for color palettes used in designing web sites. Unfortunately, the photos showing Luke's examples don't appear to be working on the site (the images have been fixed...thx, Lars), but Dave Shea published an image that illustrates Luke's technique.
When you're on the beach in the Caribbean as I was recently, it's difficult for the color palette to escape your notice. I whipped up this collection of colors from some of my photos (coming soon) from Mexico:
From left to right, you've got the pale blue of the ocean close to shore, the light brown of the sand, the green of the lush vegetation, and the deep clear blue of the sky.
Update: A couple people asked, so here are the hex values for the above colors: 3DB8AE, FFEDD8, 396600, and 0050A2, respectively.