This is a listing of my favourite iPad apps:

Dropbox – Absoutely invaluable for shifting files too and from the iPad; synchronise files between iPad and other computers; useful for collaborations

Squeezepad – Excellent and easy to use interface for Squeezebox Server.  Logitech’s series of Squeezebox audio devices are really rather a nice way of managing and playing digital audio files.

iAnnotate – read and annotate pdf files.  Aji Reader Service can be used to synchronise pdf files between Mac or PC and iAnnotate.  I use this to synch my pdf collection which I manage on the Linux and Mac notebooks using Mendeley.  Unfortunately the current version of the Mendeley iPhone/iPad app leaves quite a lot to be desired.

iWork – three iWork applications have iPad versions: Pages, Numbers and Keynote

Skype -VOIP telephony via the iPad.  No video of course, but the rumoured second generation iPad may have video.  Works well on my WiFi model iPad.

The Feed -Interfaces with Google Reader to help keep on top of your RSS feeds (I usually follow around 120 or more feeds).

Tweetdeck – Not quite as full-featured as the desktop version, but still pretty good for emitting thoughts into the twitterverse.  Has a useful browser panel.

Headspace – A kind of hybrid task manager, planning, to-do list app that is really quite versatile.  Three dimensional effects!

Wolfram – Very useful if your web searches aim to pull out numerical analyses.  Reasonably good value when I got it on special offer, but I guess one could always access Wolfram Alpha via Safari.  A bit too focussed on American data.

Notes Plus – very versatile note taking app, with diagrams and text.  No character recognition – for this try WritePad.  Works best with an iPad stylus.

Quickoffice – read and edit MS Office documents.

Penultimate – a neat and easy graphic note-taking app.  Works best with a stylus, otherwise you’re finger-painting