This plugin enables the use of Google Authenticator two factor authentication for logging in to WordPress admin.
This article lists several HTML5 development tools.
This tool from Microsoft allows you to use a virtual machine (e.g. VirtualBox) and test sites for compatibility with IE6 to IE11 on various operating systems (all the way to Windows 8.1).
This site provides user interface design examples for a variety of situations e.g. online form, shopping cart, etc.
This presentation provides various points to keep in mind when designing a mobile website.
This site provides free responsive HTML5 templates that you can be customised.
This how-to article provides info on integrating Intuit / QuickBooks payment gateway into websites.
This article highlights the usefulness of project kickoff meetings and also the aspects to cover in such meetings.