A few days ago I wanted to start the car - dead, completely dead. I pulled my other car near it, I charged the battery for a while and I started the car; I drove it about 20 miles that day to recharge the battery and came back home; next morning, my wife wanted to leave with it and tried to start it. She only tried once and because of the weak battery, the starter wouldn't (I don't know how to say that in English) make that loud click, it would only turn. I tried to start it and it started right a way (lucky me). That day I didn't drove it (I rode my motorcycle to work) as well as next 2 days BUT I disconnected the battery (suspecting something). This morning, as expected, the battery was dead again (even with after being disconnected - I'm sure that being completely drained took it very close to it's end of life) and I recharged it again from my other car but then I tried something different: I measured the current "sucked" from it.
With the ignition on (and the jumper cables disconnected), the current was something like 8A (plus minus 1A) - probably normal.

BUT (and now comes the interesting part) with the ignition off (key out of the ignition) the current was something like 1.5A (meaning a regular battery would completely discharge in about 2 days).

I found the symptom, where's the cause? where should I start looking for "trouble spots"

Thank you in advance!

P.S. I have the car for a while and the only thing done recently to it are new brakes but there's no possible way that this is the cause.

 

Well, you've already found that there is a parasitic drain, now you just need to narrow it down.

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

 

Thanks, I'll keep you posted with the problem

 

Stupid!!!
Stupid me, stupid car, stupid previous owner!
The cause? Bad positive connector!
So bad that someone had to put a screw in it to keep it from falling! Therefore it was oxidized as hell.
The leak? just the current used to recharge different capacitors the first time you connect the battery!
And I wouldn't have known that if it wasn't for a friend of mine who gave me his (new) battery to start my car and nothing happened.

That's it! I'm half pissed for what happened and half relieved that I found out what's wrong and that it's not as bad as it could have been.