ColorSuckr is a free online service which can extract colors from an image & generate color schemes.
It can be used in 3 ways:
- by mentioning the URL of the image
- via a bookmarklet
- or a Firefox add-on

Once the color schemes are ready, they can be downloaded as Adobe Swatch (.ASE) files or more schemes can be listed from COLOURlovers for any selected color.
ColorSuckr also offers the results in RSS, JSON & XML formats which makes an integration with any application possible.
Requirements: No Requirements
Pictaculous is a free web-based service which generates the color palette of an image you upload.
And, it provides color palette suggestions from Adobe Kuler & Colourlovers which can be used with the image.

Once the color palette is created, it can be downloaded as an Adobe Swatch file.
Pictaculous also enables you to send the image & get results via e-mail (which is nice for using the service in phones).
ColoRotate is a free web-based service that helps to work with colors in 3D, in real time & offers an unique experience.
Using the application, you can quickly see the multidimensional nature of colors and the relationships between colors.

With ColoRotate, you can create color palettes & save them. Its quick drag-and-drop interface to adjust hue, brightness & saturation helps you customize the colors with ease.
And, palettes created can be imported & exported in Adobe Swatch Exchange (ASE).
ColoRotate is also a color community where it is possible to browse & search themes created by other users.
P.S. You may also want to check "Learn About Color" menu of ColoRotate where it is possible to find valuable information on color like:
Requirements: No Requirements
Color Pallete Generator is a free web-based application that is creates the color palette of an uploaded image.
It supports .PNG, .GIF, .JPG, .JPEG images & creates 4 levels of palettes: light, medium, dark, complete.

The generator also prepares the related files for CSS & Photoshop swatches of the color palette created.
P.S. Up to 1 mb can be uploaded.
Color Scheme Designer is a web-based application that provides a high quality experience for creating color schemes online.
The color wheel lets users to define a scheme based on a single color or more by adding more controls to it.

With 15+ presets, ability to control the saturation/brightness & contrast levels, it is possible to switch between variaties of the color schemes created.
A great feature is the ability to preview the colors used on different outputs like a scheme or a webpage preview.
Cymbolism is a website which aims to quantify the association between colors and words with the help of the visitors.
It simply shows a word & asks the visitor to click a color, the visitor thinks the color defines.

There are currently 200 words & visitors voted more than 280,000 times for them.
Words can be browsed to see the color-palette generated from the previous votes. And, this may help on deciding which colors to use in our designs considering the theme of the website.
kuler is a color community website created by Adobe.
There are 1000’s of color sets created by users which you can inspire & use.

With an easy to use interface, kuler users can create their own color sets & share them with the community. Plus, most popular, newest and highest rated color sets have RSS feeds that help users discover new colors everyday.
Colourlovers.com is a website where you can find lots of user created colors, palettes & patterns. Download them easily, share the ones you have or ask for opinions.
There is also lots of information about colour trends, creating a colour and so..
