I used to just use the Facebook website on my iPhone, but the custom app does seem to make the UI a little easier to get around.
http://blog.facebook.com/blog.php?post=22389032130

Show off the amazing processing power of your new toy.
http://macenstein.com/default/archives/1571

Shazam is amazing! If you hear a song you like, but don't know who the musician is, Shazam will recognize it for you and give you options to purchase it. Not only is it incredibly handy--it's a rather cool parlor trick.
http://www.shazam.com

With this stunning application you receive practically every game that was ever available for the SNES, creating 1000's of hours of play time. You will never need to purchase another game ever again. Wha!!!
http://www.iphoneapps.org/apps_snes.php

AMAZING app and site. Highly recommend.
http://mobile.yelp.com/

Internet connection detector
http://spicyclam.com/idetect/

A nice, easy way to turn your iPhone into a portable hard drive.
http://veiosoft.com/

You can record video footage of any length and upload them directly to Youtube and many other video sharing websites across the internet. You can also easily upload the videos to your computer with just the click of a button.
http://www.iphoneapps.org/apps_video.php