Without getting into too many details I ended up reading a speech that was going to be given by a kid regarding hamsters. One little titbit of information that came out was that the word "hamster" derived from the German "hamstern" which means "to hoard".
Not something I knew and I was ready to add it to my mental database; first though the proof-checking. A quick visit to the Online Oxford Dictionary and their definition includes:
early 17th century: from German, from Old High German hamustro 'corn weevil'Huh how odd if it was derived from "hamstern" I would expect to see that. Perhaps the German dictionary might offer something else? Nope just the same "hamustro".
Time for a Google search for "hamster hamstern" (no I didn't mean "hamster hamster") and a large number of pages all repeating that hamster derived from hamstern; except one. Much as I hate to have to link to such non-canonical sources this really was the best one. So from the Straight Dope forums and the user Holger:
Although my trusty Kluge etymological dictionary isn't quite explicit in the details, it indicates that the noun came first (describing the animal), and the verb "hamstern" (to hoard) was coined later, alluding to the hamster's behaviorAnother quick check back to Duden and "hamstern" is noted as being "umgangssprachlich" or colloquia/everyday language.
In other words it came about the same way people can "squirrel something away" the naming word (noun) was used as an action word (verb) to describe someone/thing acting the same way. In the case of a hamster; its hoarding behaviour probably resulted in people being described as hamsters and thus their actions as the new word hamstern.
So use a dictionary and it'll give you hamustro; check various hamster sites (most likely a lot more popular with kids) and it'll give you hamstern. Which is more likely to continue to be spread about and quoted?