Brendan Gregg has a good collection of dtrace tools posted here.
Ever wonder what’s going on in your system’s memory (RAM) ? Solaris provides a mdb dcmd ::memstat , which provides the status of all the pages in memory.
Most C compilers provide the macros __FILE__ and __LINE__ that can be used to print the source file name and line number respectively. These macros come in handy when printing debug information or when using printf() as a general purpose tool for debugging.