As time goes on - after the advent of iOS5 - I've increasingly added apps that are office related. At this point, there is a tremendous capability - the iWork series, PDF creaters/readers, VueScan (a great app!), the Splashtop series, iDraw, Photoshop mobile, Snapseed, Notability, Print n Share (fills in the gaps for Airprint), Dragon, Goodreader, etc. Using DropBox could enable the file system as described above. Promising.
I have the Logitech Zagg keyboard and LOVE it! Makes all the difference when when it comes to typing long documents - and general input. Also forms a protective lightweight case when not in use.
I, too, do graphics using Creative Suite programs and THOSE have to have a full-blown computer. The other things that still make a PC/Mac necessary include USB capability, DVD reader/player (this may become obsolete, though, as streaming increases), and direct access to files (without jailbreaking) that you can organize.
Otherwise, though, it's getting very close to Steve Jobs' prediction of "no computers."