Presenting Software Architecture
Inspired by the video Presenting Architecture from You Tube.
Expansion Joints
Have a base set of slide covering typical areas, then hide and show slides depending on the audience you are presenting to. A high level managerial presentation will require different slides to a presentation to developers, e.g.:

Against:

This allows us to have all the information we need in a single slide deck, and customise to the audience by showing and hiding slides.
Accordion Slides
These are slides with no bullet slides, so nothing set in stone to read. If there were bullet points you'd usually have to address them all. Without these you can adjust the amount of time you talk about this slide to fit the time available, so if yiu are running behind schedule you brush over this slide, it you are ahead of schedule you can go into additional detail.
Use Animations
For example, when a lot of information is required on a slide you can choose to use animations to visibly show the flow through the slide.
Dimension and Focus
Highlight parts of the slide you are talking about, for example if you start with this slide:

But want to discuss the API layer for example, have the slide update as:

This draws everybody's focus to the correct part of the slide.
This can be done by adding boxes witout borders and setting the opacity to 75%-80% and animating this, or just have different slides.
Build Outs
Showing the initial slide above (the Dimension and Focus full slide example) can overwhelm the audience, every person in the room is looking at some place different to where you want their focus. An answer to that is to instead use the build out approach, which I consider much like drawing on a whiteboard live in front of the audience. We don't start with the complete picture, we construct it as we explain it.
For example, we start by talking about the client requests, so we only show this initially:

Then, as we move onto the API layer we add this to the diagram:

We have the audience attention on the API at this point. Then, as we move on we can show the first set of services we want to talk about:

We could even add opacity to the sections we have finished discussing.
Over time we build out the entire diagram, all keeping the focus of the audience and not overloading them with a completed model they will try to instinctively understand before it is explained to them.