1. Weather.

When I want to know the weather, it is just quicker to check my iPhone than find the Mac widget or dial up weather.com.

2. GPS Maps.

If I want to do some local area mapping, it is much easier firing up the Maps app and hitting the little blue button on the lower left than firing up a browser and a maps bookmark or Google Earth then inputting the current location. More complex mapping operations may require more work by the computer. This might change if Snow Leopard has Core Location functionality.

3. SMS and Phone.

I know I am being a bit 'Captain Obvious' here but with Skype and SIP apps on the Mac, I often use the computer to make calls and send SMS messages. That being said, when I want to do any of things, my tendency is to reach for the iPhone first.

4. Facebook.

The iPhone Facebook app is great and a great way to cure 5 minutes of boredom. Sure you can do more with the regular webpage, but its all right there on the iPhone.

5. Music.

At work I have my whole music collection both on my iTunes and my iPhone. I reach for the iPhone first for some reason. Perhaps it is the ability to walk around with my music on the iPhone. It certainly isn't a chore to listen to music on the iPhone (Which Steve Jobs called "The best iPod we've ever made")

6. Checking Email.

I naturally reach for my iPhone when I want to check my email. It's pretty quick and easy and I have the first 5 lines of the email in the subject line so I don't have to open most of them. If I want to write an email, I definitely head over to my desktop.

7. Contacts/Addressbook.

The Contact and Addressbok in the iPhone works well enough that I haven't opened the Addressbook on my desktop in a few months.

8. Gaming.

I actually enjoy gaming on the iPhone more than on my Mac. It may be purely psychological or maybe I enjoy the ability to take the game on the road with me, but when I want to play a quick game (GL Golf is my current favorite) I head to the iPhone.

9. Notes.

I take most of my important notes when I am on the road so when I need to get to them, they are on my iPhone. It would be nice if Apple let me sync my stickies and my iPhone notes. Until then, they are on my iPhone.

10. Twitter.

I use Tapulous to let those around me know what's up and where I am. Again, this is more about the GPS Core Location functionality than the App being better than my desktop client. It certainly takes more time to enter the data into my iPhone than it does the computer...and I can't cut and paste URLs either.

As Apple ramps up the capabilities, processor and screen of the iPhone, more and more computing tasks will be offloaded from my main machine. Am I alone? What do you use your mobile for that you once used primarily on your traditional computer?