MapBox provides a series of tools that allow you to design, host and share your custom maps. They also have a BEAUTIFUL support site!
I stumbled across MapBox while doing some research for a side project. There isn't anything more rewarding than discovering an awesome service that’s using Tender for its customer support.
"The workflow (in Tender) is great," says Will White, a developer at Development Seed who works on MapBox. "It's easy for people to start discussions, and we can quickly turn emails into support requests. It's also great that the developers can have back-channel conversations directly on the discussions."
What's even more awesome is that the crew over at Development Seed release their code as open-source software. If you do any type of mapping work, be sure to check MapBox out.
MapBox for iPad
Share maps with anyone, anywhere on the iPad.
More Info: http://mapbox.com/#/ipad