Not long ago I discovered that using a photo to choose colours for a graphic can be much easier than creating the colours yourself. This is especially true when creating very natural gradients--sampling the colours from a photo of clothing helps create subtle transitions between highlights and lowlights.

Anyway, here's the url for a website that allows you to upload a photo and it'll generate a complete colour palette - http://www.cssdrive.com/imagepalette/index.php

Unfortunately it doesn't allows you to download the palette in an Inkscape compatible format, but some might still find it useful.

Thanx for the link Micro.
Gimp can do it too and you can save the palette as *.gpl (to use it in Inkscape).
See here:
http://docs.gimp.org/en/gimp-indexed-palette-dialog.html
then import the colormap into a palette:
http://docs.gimp.org/en/gimp-palette-dialog.html

Have fun !

Very kewl. Thanks for pointing that out.