Ok, so I am totes addicted to my iPhone. A. Dict. TED. I don't have an iPhone 4 or anything, but I really, really like my 3GS. My main use of it (other than as a, you know, PHONE) is all the apps. The Hubs and I combined have over 100 in our iTunes. I'd say about 70+% are mine! I mainly use it for games, but there are some awesome "lifestyle" aids that I've come to love.
"Big Oven" - this one needs internet to work, but it's my favorite quick-recipe search. They're user-submitted, and so far every recipe I've tried has been simple and tasty, which is my kind of thing, esp. when I'm in a hurry!
"Real Simple To-Do lists" - Ok, I'll admit I don't use this one as much as I could (or probably should), but I will admit it's a good place to start when it comes to tackling big projects. They have a bunch of "to-dos" to start you thinking, and you can add your own. I used it to organize my 90's party, and it did help a bit! Plus it's free. Can't turn down free, right? Actually, all of these are free apps. Heh.
"Lose It!" - Now I will be the first to admit that I haven't used this consistently in a LOOOONG time. BUT when I was on track, I loved this thing. It's easy to add recipes and ingredients (if a little time-consuming - but not as time-consuming as other apps I've tried), and it has a chart in the app to show you your progress, which I kind of love. A good, long database of already-entered items, too! IF you feel your beautiful visage needs a little more beautification via weight-loss (I think you look great, BTW), it's a handy app.
"Mad Men: Cocktail Culture" - I think I've established that I'm a rabid "Mad Men" fan. Yes, I downloaded the free Mad Men app they advertised. Now, it actually costs money to "make" a drink other than a gimlet (but I love gimlets, so I'm set), but all the RECIPES for the cocktails are free! It's a GREAT retro cocktail resource, and every drink comes with additional trivia facts; I'm a trivia junkie, so I love that. I totally want to have a retro cocktail party and use this app to make all the drinks. xD
"Around Me" - My mom turned me on to this app. It's AWESOME if you're in an unfamiliar area and want to find a restaurant, gas station, library, WHATEVER. You can either search by category or the store you're looking for, and then it'll transfer to the standard "Maps" app for iPhones to show you how to get there from your current location! It's been a big help, I love it.
I didn't get paid to endorse any of these (and TBH, most of the apps I have are games, I use my iPhone like a Gameboy, haha), they're just a few of my favorites. Any fellow iPhone users have any apps I can try?