I have just managed to synch the audio with the slides from a recent presentation on Online Voice Tools for Language and Literacy. The original session was held in Skype. I recorded both sides of the conversation (me and online participants) and uploaded the audio to the Internet archive.
I uploaded the slides into Slideshare and used their synching audio and slides tool to create a slidecast. I'm really happy with the result and now I know how to do this I'll be doing it again. Here is the final product.
(It's 45 minutes long.)
The Internet archive also provides the embedding code so you can listen to the audio only right here: