Well, I have never done that before, but I have been to a few seminars. I guess it depends on the situation, and the technology/time available to you. PowerPoint presentations with accompanying reading materials for everyone there is a start, or just materials for everyone to read if you aren't wired at your location.
Personally, I would much rather get a packet/folder/whatever of concise, interesting, relevant material that explains what you can offer/do for me and have you go through it hitting the highlights with some Q&A time, then sit through a PowerPoint, but that is just me.