The Hitchhiker's Guide to Paris

I'm going to Paris for a well-deserved and long-overdue vacation next week (21/Aug/2004 - 28/Aug/2004).

Naturally I intend to visit the obvious tourist locations (Eiffel Tower, Arc de Triomphe, Louvre Museum, Moulin Rouge, Notre Dame, etc.)

Now usually, when I return from a trip, I find myself having a conversation like this:

Killjoy: "Did you visit the so-and-so?"
Me: "No, I didn't. What is it like?"
Killjoy: "Oh man, I can't believe you didn't go there - that's the one place you should definitely see when you go to [location]!"
Me: "Well I didn't go there. Buy hey, thanks for letting me know. I'll be sure to check it out the next time."

Bummer eh?

I want to avoid this scenario if possible. So I am asking you dear reader, in advance of my trip, to let me know about all the hidden corners of Paris - all the "must see" places that I might otherwise miss.

In fact, I'd appreciate anything you can share with me about the City of Light:

Where to eat; where to drink; clubs to visit; tours to take; sites to see; etc.

Please respond in the comments, so others can benefit from your insider knowledge in the future.