I wrote the Slicehost app. Would love to add graphs, but that data's not available yet in the API. As for the email link, that's because the app came out before the iPhone had a copy/paste feature. You don't need that anymore with copy/paste.
Do you know why slicehost doesn't just make their private API key a link in the slice manager? I'm also curious what extra level of security the API key buys. If I lose my phone people can still mess with my slices.
I thought the iphone app was a slicehost product - but are you saying you just developed the app as a customer? That's mighty generous...
