Thank you for your idea. There are a couple ways to handle this currently.
In the Activity section of the idea details page, you will see a votes section. Clicking the Votes text will show you the list of portal users who have voted (including their email address.)
You can build a report showing the details of each vote. To do this you will need to use Ideas as your primary record type and add the Idea votes record as a secondary record. The idea votes table will provide details about each portal user who voted on a particular idea.
This would be really useful. there is a relatively small customer base for our products but the number of users within a customer site will range from 10's to 1000's . we have seen examples in our current CRM of larger customers trying to game the system by getting large numbers of their users to vote. Just looking at the number of votes makes the idea look very popular whilst looking at the detail shows just 1% of customers want this feature enough to vote for it.