Couple of articles by Cal Erickson in Linux Journal on Memory Leak detection.
1. Memory Leak Detection in Embedded Systems .. read
[mtrace, memwatch, dmalloc]
2. Memory Leak Detection in C++ .. read
[dmalloc, ccmalloc, NJAMD(not just another malloc debugger), YAMD (Yet another malloc debugger), Valgrind, mpatrol, Insure++]
Another article on Using Valgrind.