BigTop graphs statistics beyond what top or Activity Monitor offer.
BigTop is part of Xcode, Apple's development suite.
Advanced statistics include counts of mach messages and system calls a process makes, single-process CPU load over time, and virtual-memory activity per process.
You can also provide addresses of other computers on your network to monitor.
As a means of graphing resource usage, BigTop has been overshadowed by Instruments (Chapter 26, "Instruments"), which offers more information from a larger and more configurable suite of instruments, over a longer period of time.
source of description: http://safari.informit.com