Clean up your code!
A few useful tools for building and testing websites.
Mobitest – Free Mobile Web Performance Measurement Tool. Mobitest also offers Mobitest open source for free.
spoon.net/browsers: Virtual browser sandbox for testing webpages. It allows you to run any browser from the web without the need to install it on your computer. Spoon.net has additional productivity resources on their site, and provides a wide selection of additional cloud based services besides the browser tester.
http://www.google.com/webmasters/tools/richsnippets: Google Webmaster Rich Snippets Testing Tool
cssfontstack.com: CSS font stack resource :: A complete collection of web safe CSS font stacks and font CSS, conveniently set up so that you can just copy to clipboard.
thedesigngrid.com: This links page has a nice collection of resources for designers, web developers, motion graphic artists and photographers. Resource links include books, plugins, templates, font foundries, blogs, and more.
This site, queness.com, has a post with descriptions of 16 Essential Web Development Online Tools. They have additional posts with tools and resources for HTML, JQuery, image editing, and more. Worth checking out.