Must Have iPhone Apps for Photographers?

[Redneck]

I'll get my first iPhone in a couple of weeks. One of the reasons to switch from a regular cell to iPhone is the opportunity to use software pieces I might need. For instance a business calendar to schedule shoots and save clients data.

What are the must have iPhone apps for photographers?
Can anybody recommend a powerful yet easy to handle business calendar?
What apps can make the photographers life easier?

[revjvegas]

Strobox is kind of cool for creating diagrams of a shoot layout.
And then there's Field Tools for doing DOF calculations if you need/want that sort of thing.

Business calendar I have no recommendations for since I sync with an exchange server, I just use the native Outlook calendering for meetings etc.

If you have a gmail account though, I think you can you can sync calendar info with it.

[Hanky]

Be careful with the notes, on several occasions I have inputed only to return and find nothing there.

[RKDauph]

I use:

Best Camera
OnOne's DSL Remote
Sunlight
Photoshop - PS Mobile
Location Scout

[JohnT]

Although I don't use it all the time, PhotoCalc is good.

[Richard-SSV]

There is a Zenfolio app for those of you with a Zenfolio account. It will allow you to access your account and view all of your galleries on your iphone. I use my Zenfolio account to share family photos with friends and family, so it's kind of cool to access any one of my 3500 + photos on my iphone.

[Todd Lambert]

I use:

Handi 5Dmk2 (a nice, digital version of the camera's manual)
OnOne's DSL Remote
Photoshop - PS Mobile
Strobox
Camera+
PlaceTagger (great geotagger - comes with an Aperture/Lightroom 3 plugin)
PhotoBuddy (the best all-around multi tool for photographers, free and great)
Photo Contract Maker (very good program for getting model consent forms signed on the spot and digitally)

[Redneck]

Thanks so far. I'm going to check every single one out.
Still no real recommendations on a business organizer/calendar?