https://trello.com/ - use trello to create to do lists for your whole team, each member can assign individual tickets that have been created to break down the job.
https://www.google.com/drive/ - a place to save and share files as a team.
https://www.google.com/docs/about/ - share and edit documents in real time.
https://www.invisionapp.com/ - great for presenting mock ups of your project, collaborate and use images of the project like links. Quick way to demonstrate how a project will look and work before touching code.
https://codepen.io/ - a playground you can code in inside the browser.
https://bitbucket.org/product - share one code base with a whole team by committing your work to a bitbucket repo.
https://www.sourcetreeapp.com/ - collaborate with everyone in your team by using source tree to show your teams repo and all the code committed so far. Easily create feature branches and work separately on the same code base.
https://www.gimp.org/ - design any mock ups or general images for project or presentation.
http://www.adobe.com/products/photoshop/free-trial-download.html?promoid=GXUTM - Photoshop any mock ups or general images for project or presentation.
https://www.sketchapp.com/ - create UX wireframes for rapid prototyping.
https://www.npmjs.com/ - packages of reusable code.
https://wordpress.org/themes/ - get ideas from pre made themes, use a wordpress theme to as a quick way to get a UI.
http://materializecss.com/about.html - a pattern library for the user interface of any project, have a base for your project and reuse coded components.
http://astrum.nodividestudio.com/ - another pattern library for the user interface of any project, have a base for your project and reuse coded components.