I have figured out this way that works. It seems that the file goes poof when you try to hoard themes. Once a theme is downloaded into the folder it is given a name like "asdsdfscsdfsdfsdfd". I copy that folder to another place on my computer and rename it.
Whenever you want to switch themes you can replace it into the original location.
(There must be an easier way though)
The themes are located here(at least on my machine)(Win 7)
I was unable to navigate to AppData and had to manually type the directory into the window.
I came across this. Which mentions the link for XP is
C:\Documents and Settings\<UserName>\Local Settings\Application\ Data\GoogleChromeApplication0.2.149.27Themes
Here the link to the page. (Maybe theres some info for a better way.)
Google Chrome Themes