C:\Users\<USERNAME>\AppData\Local\Google\Chrome\User Data
or if you prefer this notationWindows Vista / Windows 7 / Windows 8:
%LOCALAPPDATA%\Google\Chrome\User Data\
%LOCALAPPDATA%\Google\Chrome\User Data\
Useful linkWindows XP:
%USERPROFILE%\Local Settings\Application Data\Google\Chrome\User Data\
For more info (Mac, Linux), refer to http://www.google.com/support/chrome/bin/answer.py?answer=142059Google Support → Create a new browser user profile.