The web developer toolbar for Firefox
For mobile development Firefox is a great tool for checking pages as is. The latest version is Webkit compatible as are Android and iOS mobile browsers.
The Web Developer toolbar addon for fire fox has tons of options for testing web pages and web code. You can edit CSS and HTML right in the browser see what the effects are immediately and save your work you can’t beat that.
One tool that comes in very handy is the on the CSS menu, Display by Media “Handheld”, it is the only easy way you can debug your handheld device style sheet.
Royalty free icons
You can make your own icons or you can search for royalty free icons like these.
Free web fonts from Google
Since Android devices might only have 5 fonts installed and none of the web safe set web programmers are used to a font that downloads with your page comes in handy. Otherwise your page will not look the same or fit the same on different devices.
A mobile device detection script that is easy to use