At places like Geekdom or other community-building spaces, folks like me are often asked to speak on topics like fundraising, investing, hiring or culture.
Talks like this are all about providing maximum benefit to the audience.
Since audiences are variable, preparing a slide-deck a tricky approach. It's often either way above or way below the "useful-zone."
Say it's a 1 hour talk. The format I have found works well is this:
3 minutes - Intro on me and what I know (and don't know)
1 minutes - Overview of the format and rules of engagement for the session
5 minutes - I hand out sticky notes and ask each person to write three questions or topics they want to see covered.
2 minutes - I organize questions by topic on a whiteboard/wall. We create an agenda on the fly tailored to the audience needs.
Remainder - I go through and speak to each of those questions or topics. As we reach each of those topics, people are also free to ask questions or pushback on an issue.
This borrows from some of the Unconference ideas.
The most important is: If you want to make sure your audience gets the most out of your talk, let them tell you what they want. This format works well to do that.