I must be kinda lame. Don't have an Iphone, or ipad, but I've got an android phone. I love the craigsphone, & urbanspoon apps.
Dunno if there's an "I" version but I've got an app called Astrid, it's a tasklist, dayplanner type app that has seriously helped me stay on top of things with my ADD. I also love the CalorieCounter app by fatsecret (
there's an "I" version, you can add foods via a barcode scanner

) Also for health & Fitness, I'm using the cardiotrainer app. It uses gps to track my walks/runs, calculating how far I go & what my mph is. (training for a 5k in August, the Orc Stomp at Gencon.. ROFL!)
I also like
Causeworld, it's similar to foursquare, where you "check in" to different places, but when you check in, you get "karma's" that you can donate to different causes & money is then donated to those causes.
I'm going back to school Next month, so I grabbed a few apps that will hopefully help with that. Haven't played with them a whole lot, but we shall see. one is Class buddy & the other is my pocket prof. One that might be of use to you guys in the seattle area is One bus away
http://www.onebusaway.org/ it's an app that tracks the bus system up here, tells you where your bus is, & if it's on time & such.
The
Keyring app is great, you scan in your "shopper rewards" cards, & then it saves them in your phone. you don't have to carry around all those anymore, just fire it up on your phone & they can scan it from there.
There's ton's of droid/iphone/pad apps that are fun/productive. Just gotta look around.
I also like playing around with the geolocation/messaging apps like glympse & spot message