I got 2 new books:
Cost-Based Oracle Fundamentals by Jonathan Lewis (ISBN:1-59059-636-6)
Troubleshooting Oracle Performance by Christian Antognini (ISBN:1-59059-917-9)
Both are worth reading.
I will try to read and understand both of them.
Maybe I will reproduce some of their tests and will try to do my own, and maybe maybe I will post the results here ;-)