Most kitchens will have some type of colour scheme, and replacing it can give your kitchen a completely new look. Many people are now moving away from the pastel yellows and greens in kitchens, and going for darker, bolder colours like grey, navy and bottle green.
If your splashback tiles are neutral, then you may only have to change the colour of your walls, but these do need to compliment your existing work surfaces. If you have dark granite style surfaces, then grey painted walls and black splashbacks can complete the overall feel.
If you have traditional wooden work surfaces and wooden wall and base units, then a nice deep red colour to the walls can be very nice, making the space feel soy, contemporary and fresh. There are so many options out there today, but the current trend leans towards strong, bold colours, rather than faint pastel shades.