Probably e-mail and internet. I wouldn't even attempt setting up my college email on any other phone, way too confusing. The iphone made it easy for me to hook it up, and its proving very useful already. I can't wait to try it out when the semester starts- now I don't need to run to a lab or break out the lap top when I need to send the teacher an email or check whats going on around campus.
The internet is perfect because I make money trading stocks. I can log onto etrade, research, and trade. however, my new Zecco account does not work for some reason, I don't know why. If java ever becomes available this will also be more useful because of streaming quotes websites that I use.
Also, internet is banging because I have a few online classes. now, I could literally do my homework in between sets at the gym or something, or in the bathroom, anywhere!!!
I think the function i could do without is the ipod. Honestly, I don't think I would ever use it like I use my shuffle, plus, Im not afraid to step on my shuffle.
