There are more than 100,000 iPhone applications in existence. Some provide users with valuable media and information. Others plaster fake mullets on photos of friends. Here are a few you just might want to check out.

COOL AND INNOVATIVE

In 2002, James Hom was working on a lab assignment at Stanford University when he mentioned to teaching assistant Keyvan Mohajer an idea for a search engine that could find music you hummed.

Seven years later, Mr. Mohajer and Mr. Hom are president and vice president of the Melodis Corporation in San Jose, Calif. The company’s bread and butter is the Midomi iPhone app.

“Just hold your iPhone up to a speaker, and Midomi names the tune in as little as five seconds,” Mr. Mohajer says. “It even works if you sing or hum the melody.”

Midomi uses Sound2Sound Search Science, a methodology created by Melodis that searches sound against sound, bypassing traditional sound-to-text conversion techniques even when searching text databases. Basically, it’s like the function on your cell phone that recognizes your voice and finds the contact you want to call. It’s just much, much, much faster and more accurate.

Mr. Mohajer says Midomi also can instantly check out a song or band just by saying or typing the name. Midomi even shares songs on Twitter and Facebook and allows users to buy songs and look up lyrics, videos, and artist information for free.

So now when you’re listening to the car radio and digging a tune for the first time, you can add it to your music library within minutes.

Other cool and innovative apps include:

Jott - Hate that tiny iPhone keypad? Jott converts spoken words to text. It sends e-mails and texts, takes notes, sets reminders and posts to the Web sites of your choice.

RedLaser - When out shopping, this app scans barcodes and tells users if the items scanned are available online at a cheaper price.

Stanza - Read as many as 20,000 books for free with this app. Users can add as many books as possible from a large library of public domain titles, or add lengthy Word or PDF files from the computer. It’s a mini Kindle.

Pandora - This app comes in handy for those bored with their music libraries. Pandora finds patterns in user music preferences and creates customized radio stations.

FUN AND HANDY

Dan Florio remembers the movie that inspired his bladder-saving iPhone app.

“The idea came after watching the remake of ‘King Kong’ back in 2005 — a three-hour movie,” says Mr. Florio, a 42-year-old flash platform developer who resides in Sedona, Ariz.

Three years later, Mr. Florio launched RunPee, an app that lets users know which movie scenes they can miss to take a potty break (PeeTimes). There are currently 421 movies with PeeTimes in the database.

But Mr. Florio has bigger plans in mind. Right now, he’s working to make RunPee available in different languages and on other smart phones like the BlackBerry and Palm Pre.

He’d even like to partner with Coca-Cola for some cross-branding.

“Many people have commented that they didn’t get drinks at the movie theater because they knew that they would have to (go to the bathroom) during the film if they did. Now they can get the drink because I’ll tell them the best scenes to miss. So this should help theaters sell more drinks,” Mr. Florio says.

Other fun and handy apps include:

I am T-Pain – It’s basically auto-tune technology for the iPhone. It allows any user to sound like hip-hop singer T-Pain, which might be handy for those trying to score a record deal.

Can I Drive Yet? - This one’s more handy than fun. This app helps users calculate if they’re sober enough to operate a motor vehicle by entering relevant data (number of drinks, body weight, etc.). The app estimates answers using national blood alcohol standards.

BIZARRE AND USELESS

Alex Miro founded Krapps.com as a humorous dedication to all of the weird and dumb iPhone apps out there. For nearly a year, Mr. Miro and his contributors have written about ridiculous apps like the Hell Chicken (a virtual rubber chicken) and the Mystery Butt (a matching game involving you know what).

“(We write) thought-provoking articles that will leave you thinking, ‘I can’t believe Apple approved that app,’” Mr. Miro says.

Here are a few of Miro’s infamous favorites:

Hold The Button – “The object of the game is to press a button on your iPhone’s screen and never let go. Ever!” Mr. Miro says.

Sir Real Eye – Users poke an extremely realistic eyeball and watch it turn red.

iDrinkCoastr – This app turns your iPhone into a drink coaster (a picture of a coaster comes up on the screen).

Fatburner2K – Place the vibrating iPhone on your belly and supposedly “lose weight.”

Nothing App – “True to its name, this app does absolutely nothing,” Mr. Miro says.

Lifestyles reporter Shea Conner can be reached at sheaconner@npgco.com