Task Manager in OSX?

Is there a 'Task Manager' or similar tool on the Mac OS X that shows all processes, memory usage, and such?

oh, i didn't know you needed something on mac's because all your apps need zero memory and you have more than enough anyway...
and i mean programs don't use any of their huge processing power either, or why else would you want to know what is running ?
</realitydistortion>
macs fail, mac users fail harder !