Commenting on comments in general:
Clock: This is a must have for me, and I don't even travel that much. Timer for cooking, multiple alarms for multiple situations, and I may get rid of my old alarm clock soon and rely only on my phone (might as well in order to save money!). I don't use the stopwatch or the worldclock but the other two features are huge. Those of you who don't use the alarm, which can be set to go off once a day or on specific days without having to actively turn it on each day, why the heck not?

I can only think that you don't keep your iphone charged enough and don't want it to give out in the middle of the night.
Stocks: Few average people directly own stocks (most people in the stock market are in 401ks). I think for the few people who use the Stocks app it's reasonable, but for the majority, it's the most useless. This is probably the result of "Steve-down" development where he insisted the ability to review stocks from the iPhone.
I personally don't do voice memos, but there are plenty of people who find giving themselves voice memos are huge. Those are features are of lots of other phones.
The contacts icon was put in by Apple according to customer demand, but I've not heard anyone here who's said they use it. I always go into the phone icon because it's how I'm used to accessing contacts. Yeah I find it useless.
spotlight: to the few people who said they don't use this, it's probably because you don't need to A) search thousands of emails and B) Search thousands of contacts. The more records you have, the more useful spotlight is. When you have so many records in different apps, spotlight becomes more than 50% of the interface. Want to find something? Search for it and tap on it. If you have a reasonable organizational structure and far less records, you don't save time over the long run using spotlight so it's easy to see it's not useful for some.
iTunes- I never use iTunes to download songs, but I use it CONSTANTLY to download new podcasts! I don't know if there is another way to download podcasts but that's huge. And podcasts are free! Using your home PC is faster to refresh daily podcasts but I don't have a laptop to take with me, nor is my home PC always available to me, so getting new podcasts when I'm out and about is important to me.
Weather - I use the weather channel myself, but regardless of weatherbug or the weather channel, the built in weather app is pretty tame. I think some people might use it simply because it's a quick forecast and temperature, but too many of us want more than that (hello radar anyone?

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It would be nice to manage or hide apps. Hopefully OS 4.0 will have a better icon management system than the simple home screen. I'm trying to avoid going to 5 pages worth of apps, and I have four apps I'd just like to hide.