My baseline tools and resources for front-end development:

- Page speed https://developers.google.com/pagespeed/ http://developer.yahoo.com/performance/rules.html http://developer.yahoo.com/yslow/

- Valid HTML http://validator.w3.org/ http://html5.validator.nu/

- Usability http://www.userfocus.co.uk/resources/guidelines.html http://www.useit.com/

- Accessibility http://www.w3.org/TR/WCAG10/

- On-page SEO http://www.seomoz.org/ http://static.googleusercontent.com/external_content/untrust...

- Design for the web http://www.usabilitynet.org/tools/webdesign.htm

- Cross-browser compatibility http://browsershots.org/

- Mobile ready http://www.w3.org/TR/mobileOK-basic10-tests/ http://www.marketcircle.com/iphoney/ Modify Headers add-on

- Progressive enhancement http://www.alistapart.com/articles/understandingprogressivee...

- Metadata http://schema.org/

- Conversion Optimization http://www.conversion-rate-experts.com/ http://www.google.com/websiteoptimizer