There are wikis (like http://pbworks.com/) where members can all work on a single document:
or Google Docs (now part of Google Drive) that allow people with a Google account create PowerPoint presentations, Word Documents, Excel Spreadsheets, Forms (for collection of data like Registrations) and more... and then share them with others to consume or co-edit.
I would suggest playing with a number of tools. Remember, each skill you learn with one tool can usually be transferred to another. When you have built up enough skill sets, things become more second nature.
For example, try Padlet, formerly known as Wall Wisher, on online bulletin board for sticky notes. You don't even need an account. Post something you want to share, like items to bring to a picnic, and share the "wall" address with others. People can then simple post what they want to bring. Of course there are many more features, but it can be that simple to collaborate. Here is a quick introductory video, followed by the live wall... as you can see, one can embed it into a blog!
The wall above is live, and embedded in this blog post. Try it! Double click on the wall, and create a sticky note!
What tool would you like to enhance collaboration? What would it do? Is there such a tool already created? Dream about the task or project you would like to collaborate on, and do a Google search to see if such a thing exists.