The Chrome/Chromium history files (as well as cookies, passwords and others) are stored in this folders:
- Linux: /home/$USER/.config/google-chrome/
- Linux: /home/$USER/.config/chromium/
- Windows Vista (and Win 7): C:\Users\[USERNAME]\AppData\Local\Google\Chrome\
- Windows XP: C:\Documents and Settings\[USERNAME]\Local Settings\Application Data\Google\Chrome\
So all you need to do is backup those folders and then paste them into your new browser if for some reason you have to format or re-install your OS, or just use the same configuration in another computer.
I know there must be a simple way to merge histories from several users, but I just found this today so still haven't devoted time to it. Anyway, I hope someone finds this useful.