Originally Posted by Standby4321
Here's a site with a short list:
http://www.parisvacationshotels.com/cybercafes.html
While I make no representation as to the overall accuracy of the information, I can tell you that I've used XS Arena on several occasions, including less than three weeks ago. I believe they are open 24/7.
This one is near Les Halles. It opened at 10:00 AM. There is one nearby that opens earlier.