I use my iPad a lot for both work and home. It has really helped me get organized and have ready access to info. I still need my workstation for the "heavy-lifting" work tasks.
Word processing with Pages (letters, notes, vehicle info, family notes, lists). I put a lot of info there so that I can get to it easily.
Spreadsheets with Numbers (for audits, spec sheet comparisons, and whatnot)
PDF libraries with iBooks (manuals, drawings, documents, not to mention books)
Calendar and Contacts. I store a lot of useful info in my contacts.
All of the above synced up with my phone thru iCloud for broad access.
Maps, Google Earth, Best Biking Roads, GreatestRoad, - all help find locations and roads.
There is even a groceries app that syncs across four devices between my wife and me.
Plenty of news and entertainment options.
I can easily log into my workstation remotely to access files and programs.
Autocad has an app to open CAD files.
Brother has an app to print wirelessly with their printers.
Scanner Pro makes PDF documents on the fly with the camera.
I also play Words with Friends with my FIL in HI daily.
That's not to mention video/movie content and music players, etc.
And it's my daily alarm clock.
I expect my use of iPads at work will only be increasing, especially with the use of cloud computing.