my friend has a 99 alero 2.4. When the wheels are turned to either lock, there is a clunk in the front end when you start to drive away. Its pretty loud, it sounds like something rubbing and catching for a second. Im thinking drivers side CV joint... What else could it be?

Don't know specifically, but at the very least do this

Get under the car (with it on jackstands, NOT the jack. safety first)
check out the steering linkages and other parts, make sure the suspension looks firm, and try to move the wheels side to side/up down. The wheels should be firm and not wobbily.
Make sure the sway bar is tight in its mountings. Make sure the struts are firm in place and not moving. Try real hard to move all the aforementined parts, they should not move or dislocate by human force.

What you are doing is the safety checks. That way you do not have to worry about something falling apart on the road...

for the record, my Alero, a 3.4, clunks all the time, every bump, everything, its annoying as hell..probably a bad strut in my case..
I would check all bushings in the front end for sure..other than that..the ball joints and tie rod ends are non serviceable..