Thanks to everyone that +1'd my logo.
Here's a bit of an improvement, including what I think would be a good slogan.
Here. I actually took a few minutes to clean it up and do it in Illustrator rather than my quickie earlier version.

Loogs good - I think the tag line should be just 'digital cash' because cash is private and instant already

EDIT: I like that the first letter D looks like reversed C for Cash..Dash! v good
Could have animated version with the D rotating to a C and back..(rotating around Y axis if u know what i mean)