I taped all my sessions and had them transcribed, so not only do I know how long I ran over (sorry!) I also know how many words / sentences / paragraphs were contained.
See E-Commerce Optimization slides and E-Commerce SEO slides
The main reason I'm doing this is because I need to know how "long" a 45-60 minute talk should be. This is VERY helpful to me. I guess I can't have more than 200 slides right? -- ROB