1. Web Color Combinations
Need to pick colors for your site? Or give direction to your Web designer? This site lets you pick colors that match (not clash). Color swatches include the Web color numbers so you can easily recreate the combinations you like.

2. HTML code checker
HTML code errors can leave your whole site looking like it’s had a bad accident. All bold, all purple, or just plain wrong. This tool checks your code, makes sure it meets Web standards, and points out any mistakes.

3. HTML help
Stuck on how to create smart quotes, special characters, or an indent? This site has tutorials, cheat sheets, and more.

4. Google Analytics
This free tool gives you easy-to-understand reports showing how many people visit your site, which pages they look at, and how much time they spend. You can also create your own reports showing results for specific keywords, visitor locations, and cash earned from e-commerce.

5. Google Search Engine Optimization (SEO) Starter Guide
Get the scoop on SEO straight from the source. Find out how to make your site more search-engine friendly, how to name your pages, and what not to do.

Thanks to Greg for pointing out the last one.