@cynicalgrinch For Cards there are no limits and no paid plan.
We do offer Branded Cards at a paid plan. These are customizations to the standard cards to make them unique. For example, we power Airbnb's embeds:
https://www.airbnb.com/rooms/50724 (click embed this listing under "Save To Wish List" )
As well as StockTwits:
http://stocktwits.com/howardlind... (click on embed on the right)
The customer service guide for startups
Podsights
VentureForth with Howard Lindzon, co-founder & general partner @ Social Leverage