Here’s what I came across while browsing the finance section of the App Store on my new iPhone:
iTip, from palaware
iTip, from Uncouth Software
BigTipper, from PureBlend Software
TipCalc, from BAMsoft
Tiptap, from Made with Bananas
Tipulator, from tap tap tap
Tip Calc, from Charles Ying
Tip, from Carlos Perez
CheckPlease, from Catamount Software
Tips, from Kudit.com
mTip, from Pascal Mermoz
TipBuddy, from Justin Jeffress
Gratuity, from TapeShow
QuickTip, from Spare Change Software
Tippety Split, from Manta Ray Software
Out of 59 apps in the finance section, at least 15 of them help you calculate a restaurant tip. Some of them also help split a bill between diners and so on; some are free, others cost a dollar. I only glanced at a few of the apps but I can’t imagine there’s a huge difference among them. Which leads me to ask:
1. Is there such a weak demand for real estate in the iPhone App Store that it can afford to give 25 percent of its space to nearly duplicate products?
2. Is it really so hard — even while including certain variables — to calculate a tip?
3. I am all in favor of financial literacy, but isn’t the mastery of restaurant tipping too narrow a skill to demand such attention?
4. I understand that Apple has run into a bit of a buzzsaw with its $1,000 “I Am Rich” app, along with news of an iPhone kill switch, but neither of those cases involved junking up the new sleek worldvibe the iPhone has created — whereas this tip-calc overkill kind of does, no?
Now if someone wrote an app for tipping the flight attendant, I might consider it.
[ADDENDUM: To you long-tail commenters below, who write that "As a virtual store, Apple’s shelf space is essentially infinite," and "There is no physical 'space' limit in the App Store," let me respectfully disagree, at least a bit. Even when real estate is not physical, there are limitations. For instance, let's say I'm willing to browse the first 10 or 20 apps in the finance section -- and see that a bunch of them are tip calculators. Doesn't that make me a lot less likely to wade through the next 30 or 40 apps that might not be tip calculators? Here's a better argument in favor of the reality of virtual real estate: When a post on this blog is linked to from The Times's home page, traffic on that post spikes perhaps five- or ten-fold. But there's only room for so many home-page links -- which means that the vast majority of articles and blog posts on NYTimes.com never appear there, and therefore get read far, far less widely than those that do. Also, ask publishers how hard they work -- and how much money they are willing to pay -- to be featured on an Amazon.com front page of some sort. The tail may be long but fat beats skinny any day of the week.]

You’ve all seen this Seinfeld episode, right? That’s fantastic–a $2000 tip calculator.
In response to question #1, there is no demand for space in the App Store. As a virtual store, Apple’s shelf space is essentially infinite. Furthermore, I’m surprised to see someone at Freakonomics seemingly argue for a reduction in the amount of choices available to consumers.
The answers to questions #2 & #3 relate less to the difficulty or necessity or tipping correctly or splitting checks than it does to the issues of fairness that oftentimes crop up in restaurants.
Many people are worried either that they will accidentally pay too little of the bill (and be seen as freeloaders) or that they will be taken advantage of by their dinner companions. These apps provide a neutral arbiter of who pays what, confirming that the proposed payment arrangement is indeed fair to all parties. That way no one has hurt feelings.
I imagine there could be quite a demand for that.
Clearly you’ve never split lunch with a group of engineers who look for any opportunity to bust out their tech.
One former co-worker used to bring his HP Scientific RPN calculator to lunch.
Useless. My five year-old Samsung phone has a built-in tip calculator that also lets you split the bill between diners.
I hate to say it, but a date’s inability to calculate tip is usually a good reason for me to not ask for date number two. How hard is it really to move the decimal over and multiply by two? We don’t need precise figures here.
http://www.youtube.com/clintosterholz
They’re easy to write using the built-in functions and why should Apple decide which ones to post? There is no physical “space” limit in the App Store.
Your old friends at Marginal Revolution just discussed the same point.
While I side more with the Levitt view on this, if we are to tip, why not “at the rate of five bucks per hour (or at least minimum wage) for the amount of time we are being served. Assuming the waiter is doing at least x tables, he will earn at least x times minimum wage before any fixed salary.”
Otherwise, with standard 15% rules, waiters get paid less in tips the cheaper the food served. Yes, that’s what happens now, but is it right?
The difficulty in tipping is not with your typical two-person date or lunch meeting, it’s in the big parties where multiple people are haggling over what they owe and THEN think about the tip. Usually, two people get hosed: the person who actually takes the time to figure out their cost and the server who loses out on the tip because by the end of the haggling everyone’s so fed up at chipping in.
I’m sure there’s some game theory in here somewhere about cheapskates not pitching in on the bill. My feeling is that up to four people can split a bill easily; a fifth person makes things awkward, generally.