Kaosweaver - Home of Dreamweaver Extensions
HTML color converter. Convert HEX mode to RGB code. hexadecimal color chooser
colr.org
Generate color schemes from Flickr images, your own images, or websites. Tag schemes with something unique so you can find them again.
Five Amazing Color Palette Generators - ReadWriteWeb
5 color palette generators in the post, but more in the comments.
Test your web design in different browsers - Browsershots
Enter your URL and see screenshots in numerous browsers. The service is free, but pictures expire about 30 minutes after you make a request. It's fine for a quick check, but be sure to save the images locally if you need them long term. Nice way to test what your pages look like in, say, Linux even if you don't have that available.
Vischeck: About Vischeck
Tool to show what web pages and images look like to someone who is color blind
WAVE - Web Accessibility Evaluation Tool
Check website accessibility with a free tool from WebAIM. You can enter a URL, upload a file, or paste HTML code. There's also a Firefox toolbar that lets you check content that is password protected etc.
Repper - create your own patterns!
Create a kaleidoscope-like pattern with any photo or image. Images are licensed CC-By-NC
Accessibility tools, web developer tools, wizards and markup generators | Accessify
Create accessible forms, YouTube captions, skip nav links, etc.
Responsinator
Enter a URL and see how it looks in different widths. Simulates iPhones and Android devices in portrait and landscape. Could be useful for testing responsive projects.
BugMuncher - Website User Feedback
Add a feedback button to your website that lets users highlight areas with problems and make comments and suggestions. Screenshots and user browser info are automatically logged. I wonder if this could be used for collecting feedback on elearning, both during formal review cycles and to collect ongoing feedback after courses have launched.