If you need to create diagrams, Gliffy is a web-based diagramming tool (http://www.gliffy.com/)
If you want to collaboratively edit web pages, you can try something like Wiki Spaces (http://www.wikispaces.com/) or PBWikis (http://pbwiki.com)
If your work is mostly text, a blog might work… To make it work as a presentation, just post entries sequentially and use the ‘next’ link
There are online to do lists like Remember the Milk (http:// www.rememberthemilk.com/) and online organizers like BackPack (http:// www.backpackit.com/).
Most of these have at least one level of free service you can sign up for.