SlideWiki includes tools that help with structuring your deck.
Each deck can contain sub-decks. These can be used as:
Folders containing slides on a similar topic
Slides to be delivered in a session. This can be useful if your deck covers topics to be covered over a number of sessions or contains material to cover a course.
A deck created by another user (under development). In the future you will be able to add a deck created by another user as a sub-deck of your own deck.
Each deck and slide have a unique ID. They also have a title that is displayed in the deck tree and can be edited there. The deck and slide titles are to help with organising your content and so are not automatically displayed in the presentation mode.