8 books - yikes!!!!
have read the link from gator and part of the link from ahsan. (thanks both!). ahsan - your link looks pretty comprehensive and i'm going to try to read it all.
in all the qur'anic verses given, the word "riba" (and not "faeda") is used, as crayon said. and they do seem to point to usury = devouring - charging excessive fees. yet i find that many muslims think interest is haram, full stop. (as you brits say) some even go so far as to say it is forbidden to work in a bank. if you followed this it would mean that you could probably never buy a house or even a car to get to work.
i can see that this is indeed a vast subject and there are many different opinions. even islamqa (which is normally pretty black and white IMO), allows that:

"does that means that the scholars are agreed on all forms of riba? The answer is no; there is a difference of opinion concerning some forms of it. This is like what we have said about zakaah being obligatory according to consensus, but despite that there is no consensus on every form of it."

http://www.islamqa.com/index.php?ref=22339&ln=eng

by the way - the article on islamqa also raises another intersting question. i was really surprised to read this. it says that:
"The belief that the well-known obligations are obligatory and that the well-known prohibitions are forbidden is one of the most important basic principles of faith, and the one who rejects that is a kaafir according to scholarly consensus."

is that true? i thought it was only a few specific things that took you outside of islam.