Here is the list of tools/libraries I built so far to assist you with Alexa Skill Development

APL Designer Visual Designer tool for Alexa Presentation Language. In additional to existing alexa components some more pre-built reusable layouts will be available. The projects can be saved and shared.
Export as AVG (Illustrator) Adobe Illustrator Plugin to convert any vector file to Alexa Vector Graphics
Export as AVG (Inkscape) Inkscape Extension to convert any vector file to Alexa Vector Graphics
SVG to AVG Convert svg file to Alexa Vector Graphics from the browser itself
APL Transitions Collection of nice transitions for APL components implemented with AnimateItem
Marketing Assets Creator Create social media assets in various formats for your alexa skill. This is a simple to use tool adhering to marketing specification set by alexa.
Proactive Events Sender Tool to send Proactive Events from the browser itself without having to go through multiple api calls
CSS to APL Animation Convert css keyframes to apl animateitem commands
Speech Markdown Editor Interactive editor for Speech Markdown