[Vince Ferrer]

Knowledge is so specialized today that any one time traveler would not have the amount of knowledge to be able to develop a whole current technology in the past.

If I travelled back in time, maybe I could develop some water and sewer techniques they didn't know about, and some basic sanitation practices.

[cripplecreek]

You should read “The Variable man” by Phillip K Dick. Its a short story written in the 50s. You can probably find it for free on the Gutenburg project website.

In the story a handiman is plucked out of WWI era Europe and taken to the super specialized world of 100 years from now and creates all kinds of chaos due to his “variability”.

[smokingfrog]

You could invent the flush toilet, and we’d all be visiting the Vince every morning.