The prstat statistics utility shows a top-level summary of the processes that are using system resources currently.
These commands can be run against a specific process, but most of them can also be run against all processes on the system.
The pgrep command lets you specify the criteria and then displays the information only about the processes that match the criteria.
The prstat command displays information about processes similar to ps and pgrep commands but refreshes (updates) the output in a periodic fashion
With Solaris 9 and later, comes an extremly nice mdb command for checking how much memory is used in kernel, and how much is used in user space.