This is the list of app that I use almost everyday at my current startup on my iPhone and recommend to my team internally.

1. CardSnap ($14.99 for pro or $0.99 for base version) - Great way to scan visiting cards into your addressbook. Take a picture from the iPhone (works only with 3GS) and the app does the rest.
2. Yahoo Messenger (Free) (or Beejive at $9.99) - Both of these apps have built-in push notifications. Great way to stay in touch with your team when you are out of office. Beejive works for MSN, AIM, ICQ, gtalk etc besides Yahoo IM.
3. Evernote (Free) -  the best notes taking app there is. I do not know if there is a better way to capture notes. Use it to capture notes during the meeting, take pictures of the whiteboard after the meeting and to digitally capture all the odds and ends that life throws your way. Works from your iPhone and your desktop.
4. ScannerPro ($6.99)- This applications can scan any paper document (multiple pages) and save it as PDF. The PDF can then be emailed, send to evernote or send to dropbox. It also mounting of iphone as a network drive to allow quick transfer of documents from a Mac or PC.
5. Google Analytics ($2.99 for Pro or Free for base version) : You need this if you are a web startup. You need to know all the time how visitors are doing on your website.

Other apps that I have on iPhone but I realize I do not use as much as I thought:

• LinkedIn - I do not do enough contact research on iPhone I guess
• TripIt - Might useful if you do many trips but not otherwise
• Skype - great app. good voice quality. but very slow for voice. I think I would use it a lot more if it has push notifications.
• JiraMate - I need an app for my Jira. Unfortuately, this is not a good choice today. I have blogged about lack of a good Jira app on iPhone.
• Snatch - Great way to control your slides and presentation from iPhone. Unfortunately, its a little clunky and immediately brands you as a dork in a new group.

1. TripIt: Now available for iPhone. forward your trip emails (from airlines, hotels etc) to tripit and have then available as organized trips with offline access on your iPhone. Very useful for people who travel a lot.
2. Kayak: Book the next flight home while you are in the cab going towards airport !! Or find out the cheapest hotels as soon as you get off the call with your customer.  Call airlines or hotels at the touch of a button (they have phone numbers for all of them).
3. Evernote: A great note-taking application for your iPhone.  Take Notes in meetings, Take pictures of whiteboards. Record people as they talk. Sync it all back to your Mac (or Windows) automatically over the air.
4. LinkedIn: Your LinkedIn on the phone !! Learn more about the person you are about to meet or search contacts in your network on the fly !! And yes, its free.
5. Nexonia Expense: Note down your expenses on your iPhone as they occur.  Have it all automatically sync to a web application accessible from desktop. Take pictures of your receipts or fax them to an 800 number. Export nice expnese reports to HTML, PDF or EXCEL.
6. RowMote: Using your iPhone to flip your powerpoint slides for every little meeting gets old soon but its still worth doing it for those big conference rooms or large meetings. Works with both Keynote or Powerpoint (also controls FrontRow, DVD, VLC and lots of other apps)
7. Yelp: In a new area and do not know what will be a good place to grab lunch (or dinner of your favorite cuisine). Why not go where locals go - using Yelp!!
8. Tip: There are dozens of tip applications in the appstore. Some are even free. But i like this 99 cents app. Its has the highest rating of all tip apps and it am
9. Cheap Gas:  Find the cheapest gas prices near you. So okay, company is paying for the gas in your rental but you can still use the app to find the nearest gas station (and if there is one across the street that is 6 cents cheaper, it wont kill you to use that!!).And yes, its free.
10. Kindle for iPhone
    
    : Carry your entire library with you on your trip and read whatever you feel like - with no weight !!

1. Evernote: This is a great note-taking application for your iPhone. Your notes automatically stay synched with the peer application on your Mac (which is a great application in its own right). Besides, its free !!
2. OmniFocus: Perfect companion to your mac version of Omnifocus. Note new action items and complete action items anywhere. Must-have if you are fan of GTD.  Syncs automatically with your desktop.
3. TripIt: Now available for iPhone. forward your trip emails (from airlines, hotels etc) to tripit and have then available as organized trips with offline access on your iPhone. Very useful for people who travel a lot.
4. Kayak: Look up the cheapest fares and hotels or book the next flight home while you are in the cab going towards airport !! Call airlines or hotels at the touch of a button (they have phone numbers for all of them)
5. LinkedIn: Your LinkedIn on the phone !! Learn more about the person you are about to meet or search contacts in your network on the fly !! And yes, its free.
6. RowMote: So okay. Using your iPhone to flip your powerpoint slides for every little meeting gets old soon but its still worth doing it for those big conference rooms or large meetings. Works with both Keynote or Powerpoint (also controls FrontRow, DVD, VLC and lots of other apps)
7. Yelp: In a new area and do not know what will be a good place to grab lunch (or dinner of your favorite cuisine). Why not go where locals go - using Yelp!!
8. Tip: There are dozens of tip applications in the appstore. Some are even free. But i like this 99 cents app. Its has the highest rating of all tip apps and it am
9. Cheap Gas:  Find the cheapest gas prices near you. So okay, company is paying for the gas in your rental but you can still use the app to find the nearest gas station (and if there is one across the street that is 6 cents cheaper, it wont kill you to use that!!).And yes, its free.
10. Bloomberg Mobile: Catch up with the day's business news. Review your stock portfolio. On the go.