Introduction to relativity books 
Possible Duplicate:
Getting started general relativity 

I am an engineer who loves to read science fiction books especially when there's more science than fiction but usually I see that I lack the knowledge behind many of the relativity concepts in the novels. I've always felt curiosity in relativity so I decided that it was the time to buy an introductory book. I went to amazon and checked that there are dozens of "Introduction to general relativity" books in there.
So here's my question: What book would you recommend to someone not matematician nor physicist but with (some) mathematical background as an introduction to relativity?
 A: The answer to the question depends largely on various factors, therefore there is no point to list all books I know of. A couple books, however, stand out for an "informed" laymen. One by George Ellis and Ruth Williams, and another by Bob Geroch. 
http://www.amazon.com/Flat-Curved-Space-Times-George-Ellis/dp/0198506562/ref=ntt_at_ep_dpt_1
http://www.amazon.com/General-Relativity-B-Robert-Geroch/dp/0226288641/ref=sr_1_1?s=books&ie=UTF8&qid=1316698577&sr=1-1
Both are elementary, but very lucid and didn't sacrifice sophistication of physical principles behind. I would, indeed, recommend both to any serious students of relativity.
Another good source [will be better soon] is relativity site of ComPadre, The spacetime Emporium. 
http://www.compadre.org/relativity/
You may find many online sources there.
A: There is an awesome introduction to relativity, which puts the emphasis on understanding (including different paradoxes) while reducing the mathematical tools only to the necessary ones:

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*Andrzej Dragan, Niezwykle szczególna teoria względności (in Polish, Exceptionally special relativity)

(If, for some reason, you do not understand Polish I recommend to keep bugging the author to translate it :).)
EDIT: Now it is in English, published Dec 2021: Unusually Special Relativity!
