I have been looking long and hard for a way to project slides remotely. I once proposed, on my site, that the ideal solution might be AJAX-based. I used with some success Webhuddle and even wrote a script to convert PDF files to a zip file of gif images for this purpose, but I don’t like to rely on a Java applet. I further tested Vyew which is AJAX-based, but found that it had unacceptable limitations (like the 50 slides limit!).
Finally, I found what I was looking for! slidePresenter is a great piece of software you can install on your server. It requires PHP, but is free software.
It works in a very simple manner. Clients connect to your site and see an image. You also see the image, but can press a forward (or backward arrow) to move the presentation forward (or backward). As you change slide, the client automatically changes slide. Installing it requires about 30 seconds. Uploading your slides is a bit trickier. If you have PowerPoint or PDF slides, you first have to convert them to images. In my case, I had to done some manual work to get slidePresenter to see my presentation, but the author will no doubt improve this over time.
Assuming you have a videoconference setup, using Skype for example, then you are ready to give (free) talks all over the world.