This is a terrific post, one of the better pieces of thinking and writing I've ever seen on presenting, well done.

I've just finished a twenty year run as a presenter and have done thousands (1000s) of talks to audiences small to very large all over the world. I absolutely agree with everything in your post and all of the comments (so far) are spot on.

Given the "throwing up" nature of your post, I'll add some techniques that I've found useful:

1. Make sure you're in the room early and talk with people as they arrive. Not just casual conversation but serious stuff, including a bit about topics you might cover in your talk. Keep that going as you set up your AV, pour water, etc.

Then, when the talk begins you're already moving, already revved up on the topic and you have people in the audience who you can have eye contact with who you are somewhat familiar with.

2. If you lose your way, start to implode in self-consciousness (it happens to all of us, it's not a matter of if but when) here's a way out:

Ask a question of the audience. Even a somewhat rhetorical question. Like Rands says in the post (walking across the stage), this small pause will give you a chance to catch your breath, recompose yourself, etc. Take some discussion (no matter how large the audience) and when you catch your stride again, move back to the main topic.

3. My talks tended to be like Eddy Izzard standups but sometimes I got lost trying to weave it all together at the end. If this happened I simply asked the audience for help, saying, honestly, that I was getting older, losing my memory and a breeze came through and blew away my bread-crumbs. The audience was always happy to help me find my way back and generally, the pause helped me regain my composure.

For what its worth a number of years ago as I was trying to find a way to stop presenting I made a laundry list of things for presenters to consider. It's not what your post is but it might be useful to those reading here: Tips for Presenters.