Here are some tools that might be helpful if you’re creating websites.
The first one is GNOME Colorscheme which allows you to generate a variety of colorschemes from a single starting color. Note that there are many dependencies when you’re trying to compile it from the source code.
The second one is LinkChecker which allows you to check your website for broken links. I like the HTML output:
linkchecker -o html http://www.example.com/ > output.html
And if you don’t know the Web Developer Toolbar for Firefox yet, check it out!