There are some Chrome extensions out for this.
I personally like this one because it tells you how long is left until the page automatically refreshes. (For those like me with slight OCD tendencies :)
or there is Auto-Reload which has a few more options under the hood.
Please note: You need Google Chrome version 4 or higher to use extensions. The current version is 4. The development version is 5. Since Google Chrome automatically updates itself (in most cases), you should already be on 4.
You can find this out by clicking on the wrench icon on the right hand side and seeing if 'Extensions' is listed in the drop down menu.
Alternativelly just type
chrome://extensions/ in the URL address bar. You can then book mark this page if you so wish.