Each time Google Chrome gets updated, it leaves behind the old version of Chrome. While this comes in handy when you have to downgrade, it also builds up (precious) hard disk space. You can, however, manually remove the old installation files.

Google Chrome is installed by default in your local profile folder, at:

Location

%USERPROFILE%\Local Settings\Application Data\Google\Chrome\Application

In that folder you will find the main executable (don't remove that) and the different versions of Chrome.

You can simply delete the lower version numbers so that only the highest version remains. This clears out on average 80-100 MB per folder (although it could very well be much more).