What are the top legal apps being used on tablets (if such a thing exists)?

I've been searching around and can find very little in the way of specific legal apps - and I'm talking about productivity tools here, not acquiring information. 

I come across a lot of people to take their iPad to work simply to read and respond to emails and I've yet to come across anyone who has replaced their PC/laptop with a tablet.

Do you have any information, ideas or tips for making the most of the device?