Apple Apps - these are the apps that Apple has already included on the iPad
Calendar - I used to use an aftermarket app to keep my calendar. The updated calendar does what i need I can sync my google calendars and show more than one calendar on the screen.
Mail - the mail app is also upgraded and fully usable for me.
IBooks - I read ALOT. Mostly public domain and books from project Gutenberg. It's easy to get books in and out of the iPad
Pages - It's a basic word processor and it does an ok job. I"m not sure I'd want to write a dissertation on it, but it's doable. It outputs to keynote, pdf and Doc files and it emails as well as sends the files to other programs that you can print from.
Keynote - It works just fine. It's supposed to be about the person giving the presentation and the content, not the platform.
Numbers - It's on there but I haven't played with it yet. Numbers make me nervous.
Video - I've got megs of YouTube video's that I used real audio to download and convert to a format that works on iPad and iPhones. I've got pt and staff teaching tools on it. I've also got a couple of movies.
Music - what can I say, my music tastes are pretty eclectic. And I have lots, hours and hours of podcasts
Printer Central - that allows you to see what you have saved on your pc.this app allows me to print just about everything. It's a two part program, one part on the iPad and a small server on my PC
Instapaper - This app allows you to save pages and view then later. It also has a web interface so you can see your saved pages from other computers. There are a number of instapaper aware apps the will save pages. Twitterific for one.
Papers - this is an App that functions as a reference library. I've got all my PDF files that I use as references in it. You can get.
Goodreader - this ISA file management app. it allows you to download files, view and manage them.
Newsrack - This is what I'm currently using as an rss aggregator
Calculator XL - A calculator with big numbers