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.
Thanks for everyones responses. The XS Arena looks promising (either of the Les Halles locations), and it should be too far from where we're staying. I'll likely take my laptop anyways and see if I can luck into a neighbor with an open wireless network, but won't count on it.