u can trace a person from his Ip address only if its the Static Ip Adrress.
Genrally Ip address are Dynamic.
For Eg: 219.64.79.81 is my Static Ip Adress but i am assigned ip Dynamic or INternal IP address of 172.16.3.121. Similarly my friends are belong same Netwrk and they are assigned a diffrent Ip ADdress like 172.16.3.207.
But the common thing is that We all share SAme Static (External) Ip Adress.
Thus if u try we find either or both or all of us, u may get the Same External( Static Add Foresaid.
The Bottom line is that U may rarely find a person with his Ip address.
THis Website is usefull for Finding the persons Geographic loc given his Ip add
www.dndstuff.com