Garr Reynolds explores the blur between slides and documents that makes so many presentations poor and ineffective:

Projected slides should be as visual as possible and support our point quickly, efficiently (good signal-to-noise ratio), and powerfully.

He suggests (correctly) that some of the blame lies with conferences and corporate visual guidelines that force a speaker into a catch-22: produce those powerful, visual slides, or produce a document to be read later:

What results from trying to kill two birds with one stone is the “slideument.”

Conference guidelines and corporate rules and corporate cultures concerning the “correct way” to make presentations reinforce the legitimacy of the slideument.

This is an area where wikis can help – both technologically and culturally. Since a wiki emphasizes an active, changing flow of text, it’s an excellent place to map out the content of your presentation. Then you can take the content in multiple directions: into a more detailed narrative that’s better suited to posting on a blog or conference website, and a visual presentation that you’ll deliver in person at the conference.

This is how I develop all my presentations – both for conferences and clients.