Trello is a great system to look at for ideas with this implementation. Their basic layout with “Lists” as columns (equivalent of “Deal Stages” in HubSpot) and cards (Deals) and how they have a basic color label system and the ability to choose which fields will be displayed on the front of the card.
When customizing the deal fields it would be great to have a checkbox or way to determine which fields would appear on the front of the card. And not to mention, for heavens sake please give us the ability to disable automatically putting a close date on deals!!!