I use Fing to map out networks. It's a bit cumbersome in that you have to manually force a scan sometimes, but it works very well 99% of the time. Alternatively, Net Master HD. Ping analyzer just for my very very basic ping needs. Subneter because I got it for free, usually don't need a subnet calc anymore.
System Status (orange/gray icon) for pretending to have a task manager. Kinda neat to have a look at the syslog and other stuff.
Speedbit HD for YouTube whenever I tire of the mobile YouTube website.
Planetary to listen to music in style.
Got tired of tunein radio pro eating up storage space, plus I didn't really need all those features. So I got Tunemark, which isn't as good, but suits my requirements.
GoodReader and PDF Expert for all my PDF reading needs.
Kindle for those sweet sweet amazon ebooks.
Math Ref because I need to do some light math sometimes.
WebDAV Nav has a confusing GUI, but eh, whatever works. Does what its name implies.
DisplayLink & Splashtop let you use the iPad as monitor or allow remote desktop access, respectively. Works flawlessly.
IPrinter to turn the iPad into a Printer. Easy way to send over documents and convert them to PDF at the same time.
MiCal HD because it's a bit better than iCal for what I need.
m's dictionary for my offline dictionary needs, useless for non-Germans, but hey, you never know.
Photogene, Snapseed, Photoforge 2, and a bunch of other image editors.
Aceplayer and the now defunct Gplayer for "unsupported" media. Apple.
Easy QR for QR code scanning/generating. Crappy iPad 2 camera is my enemy.
KitchenPad, because my timer needs to be obnoxious to set up and ... Dunno, really. I like it for some reason.
Appshopper to keep tabs on which apps are discounted and stuff. Also AppZapper HD, but that one's inferior.
DuckDuckGo because I'm a rebel and shit.
Skobbler 2, worst name for a Navi app ever. Openstreetmaps only, but cheap, and offline.
Vydia:
circuit coder (you will probably hate this)
Cradle of Rome (match those jewels! Match them good or you'll get the whip!)
Spirits (Lemmings)
Hexapper (Minesweeper on a ball)
DropZap 1&2 (minimalistic Tetris-y puzzler that's hard to describe)
Math Matrix HD (maths as basis for a game, what could possibly go wrong?)
Time Garden (I like matching games)
Where's my Water & Feed me Oil (physics puzzles, get liquids to the target)
Beyond Ynth HD because the main menu music is just too awesome
Giana Sisters, league of Evil 1&2, mos speedrun, ...also shantae but don't get that, it's a rather loveless port (Jump'n'Run games)
King Cashing (Las Vegas meets RPG)
Infinight (Survival Horror, kind of)
Spider: Bryce Manor HD (You are a spider. Eat insects. Explore.)
4Towers, Creeps HD and many others (Tower Defense)
Jet pack Joyride, Robosurf, Sea Stars (pres butan to fly, durr)
Dark Dot (conquer the world as a dark dot. Squeak menacingly.)
Also others, but I'm losing interestOOOOOH A SQUIRREL
