The number of processor cores available in high-performance computing systems is steadily increasing. In the latest (Nov 2007) list of the TOP500 supercomputers, 86% of the systems listed have more than 1024 processor cores and the average is about 3300. While these machines promise ever more compute power and memory capacity to tackle today's complex simulation problems, they force application developers to greatly enhance the scalability of their codes to be able to exploit it. To better support them in their porting and tuning process, many parallel tools research groups have already started to work on scaling their methods, techniques, and tools to extreme processor counts. In this paper, we survey existing profiling and tracing tools, report on our experience in using them in extreme scaling environments, review existing working and promising new methods and techniques, and discuss strategies for solving unsolved issues and problems.