Has anyone ever been to phnom phen? i am thinking about going do u know anything i have to do while i am there

Been there a few times...

Some of the sights you have to see are:
Tuo Sleng, former torture prison of the Khmer Rouge....
The Killing Fields outside of the city...
You have to go to many of the shooting ranges (also outside the city)....
The museum.....lots of cool artifacts to see there..

Downtown bars, including:
Heart of Darkness...be careful
Shanghai.....the most beautiful girls in Cambodia, honest!
Sharkeys.....good rock bar, some scary looking women in there
Walkabout Hotel....a classic hangout, open 24 hrs, women are even more scary looking than Sharkeys..but it's all good