Whatsapp - free msg and chatting ( for a small fee)
GoodReads - (book club fan) (Free)
YR.no - free accurate weater app (free)
PS Express - Adobe Photoshop (Free)
Uscape.it - Panorama shots (photography) Free
IMDB - great for researching new movies, Tv shows, actors - anything to do with TV/Film
A cool way to drain your battery quickly before recharge is Pocket Pond HD (US store only), also shows off the iPad's graphics pretty well . If you're really bored while waiting, buy the full iFish Pond which also adds fishing.