Use
I use my iPad for:-
A) Note taking in meetings
B) To do lists
C) Mind maps
D) One to one Keynote presentations using screen
E) Use with projector for Keynote presentations
F) Document creation and editing
G) Spreadsheets
H) Web browsing for fun and for work
I) Diary/ calendar
J) Address book
K) Read books (iBooks)
L) Read newspaper I subscribe to
M) Use iDisk
N) Read PDF documents
O) Occasionally print (Print n Share)
P) Transfer photos from digital camera
Q) Occasionally Youtube
R) Occasionally watch films (screen really good for that)
S) ITunes University
T) Podcasts (particularly BBC Radio 4 - Material World, A History in 100 Objects, In Our Time, Great Lives)
U) Email (of course)
V) The Elements (for fun)
W) Voice recording thoughts, comments and ideas for work
X) Use of maps to find out how to get to places
Y) Chambers dictionary and Thesaurus
Z) Weatherpro (use for work along with other weather systems paid for by company)
AA) Facebook a little bit (To annoy a niece and keep in touch with a cousin)
BB) IMDB for researching movies to watch and to occasionally answer questions
CC) Viewing photos
I used to use my iPhone for much of the above. I have replaced it with the iPad wifi & 3G. I use my iPhone a lot less now. The larger screen and keyboard are brilliant. I have a wireless keyboard for larger documents, which is great as it makes for a bigger screen (keyboard on screen hides itself).
I actually used my iPhone more than my PC laptop, Powerbook, net books, PC's and Mac Mini. I now use my iPad instead of the IPhone for the above. My eyes don't hurt so much now either.