I have been playing with Kuler for a while now and I notice that with every image I use to create a palette from, Kuler pulls almost exclusively from the far left side of the image. In some instances every color has come from just the left edge of the image.
I've also noticed that with some images the choices of Colorful, Bright, Muted, Deep, Dark aren't each a different palette. In one instance three of those choices produced the exact same results (all from the left of the image of course).
One thing I'd like is the ability to select the area in the photo that Kuler samples from.
Of course I'd also like to see Kuler sample from more than just the left side of the image as well.
Another suggestion, since I seem to be full of them just now. The ability to have more than one pallet open and drag colors from one into the other. Right now when you get colors from an image you need to save the pallet then open it in the editor and read the color value, then open the palette you want to work on and type in he color values for the color you want to move into that palette.