Valgrind, the amazing profiler

Valgrind was already some versions ago a very good memory leak checker, but it is fastly becoming the most amazing tool for profiling, freely available for all the developers out there...

It is now composed of a myriad of tools:

Memcheck to check memory-management problems
Addrcheck whihc is a lightweight version of Memcheck, that just checks for bounds.
Cachegring which is a cache profiler to help you reduce cache-misses.
Massif which is a memory heap profiler, to help you reduce memory consumption.
Helgrind which is a thread debugger which helps finding non-locked accesses to shared data.
Callgrind is an external tool that enhances Cachegrind to include a call trace and timing and comes with a very good GUI: KCachegrind