A few nice nature image images I found:
Nature - Parana River delta, Brazil
Image by Trodel
False-color composite image made using shortwave infrared, near infrared, and green wavelengths of the Parana River delta. This image highlights the striking contrast between dense forest and wetland marshes, and the deep blue ribbon of the Parana River.
Picture by NASA acquired by Landsat 7
1680x1050
Original at http://visibleearth.nasa.gov/view_rec.php?id=2592
Nature's finesse
Image by Pensive glance
The original image of 'Like waving under the wind'