1. Underlined text.  Underlines are the international identifier of links.  So unless your text is linked, it shouldn't be underlined.  Otherwise people will try to click on it and then wind up hating you when it doesn't link to anything.  If you need to emphasize something, use bold, italics, or quotes.
2. Spaces in links.  (I wrote about this a while ago.)  Or I should say "spaces at the beginning or end of links."  Many web publishing tools allow you to create links by double-clicking on your text and clicking the "Insert Link" button.  But when you double-click on a word, it automatically selects the space immediately after the word or string of words.  And links like this or this look stupid.

1. Apps.  I understand what an iPhone App is, and I realize there are a lot of other people who also understand this, and there's some sort of exchange of money involved, which has a positive impact on our nation's economy.  That's great and all, but there are like eleventy jillion people who, like me, don't own an iPhone, so all this talk of Apps and App Stores and whatnot is simply meaningless.  It's one thing to have a mobile version of your website so non-iPhoners can play along.  But as soon as you create an App, you've just alienated approximately eleventy jillion people.
2. SMS character limit.  Apparently the iPhone lets you send text messages that are longer than the industry standard 160 characters, which is fine and all because the messages are simply broken up into 160-character chunks, but which is pretty stupid for the countless (I've heard it's around eleventy jillion) people without iPhones, where these chunked text messages show up as separate (and often numerous) chunks, sent by some stupid iPhone user who doesn't understand how text messages work.  But this isn't a user issue; it's a software issue.  One simple workaround would be to show the user when their message is going to be split up, which would hopefully encourage them to be more concise.
3. "Sent from my iPhone."  First of all, I don't care where your email comes from.  That goes for you too, Blackberry weirdos.  But I'll concede that there's occasionally value in knowing why an email doesn't contain complete sentences and sounds like you're mad at me.  But at least Blackberries are used by working folk.  Yes, iPhones can work with corporate email too, but honestly, who on earth has a work iPhone?  Like four people in Silicon Valley.  The rest of you are simply flaunting the fact that you own a coveted piece of technology.  Yes, I'm jealous.

Windows [3.1, 95, 98, 2000, XP, Vista, 7]
... or ...
Office [95, 97, 2000, XP, 2003, 2007].

1. Navigation.  The clickwheel was a novel concept, and it's good for moving quickly through long lists of albums and songs.  But it doesn't have fine-tuned control, and that's a problem.  Pretty much every time I try to navigate to a specific item in a list, I accidentally overshoot it by one, then I overshoot it again on the way back.  A solution would be to give the user some tactile feedback so he/she could "feel" each item in a list, kind of like the volume dials on many car radios.
2. Scratches.  The screen gets scratched easily, but oh well.  The more easily-fixable scratchable surface is the beautiful stainless steel on the back of the device.  I realize a scratched back surface doesn't affect the functionality of the iPod, but it's the thought that counts.  One solution would be to use titanium, or some other light, hard metal.  I would say tungsten, but it's heavy (unless that's what you're going for).
3. Podcast sorting.  Podcasts are essentially recorded radio programs, and they're broadcast in chronological order.  So why would I want to listen to the newest one first?  That's how the iPod does things, and I would at least like the option to do things my way.

if (largerimagesize > currentimagesize) {
   display_link();
} else {
   do_nothing();
}