All of the above
I have a tablet pc which has remote internet connectivity via cellular connection. I have a cell phone and 3 lines in my office. I can access my files in the office from anywhere in the world, which helps alot.
Quickbooks is nice for billing but I designed my own CRM and am working on a module for scheduling. I have named this software "Office Manager" but never plant o release it. It's just for my own company's needs. This office manager will eventually become the backbone of my office automating as much as posible... might even repalce quick books one day... Maybe.