Google (free) - The Google application sets up a Google search page. There's also a link to other Google products like Mail, Calendar, Blogger and Reader.

New York Times (free) - Articles and news from the New York Times. The pages are updated regularly so you can read the complete text of news articles and features. Occasionally the program will just crash and send me back to the iPhone's Home screen. 

MLB.com At Bat 2008 ($4.99 for this season) - I'm a baseball fan. At Bat delivers up-to-the-minute information about Major League games, including a pitch-by-pitch description. The program works well, although the video plays sometimes lock up, even when I am watching on a Wi-Fi network. It seems that next year, we'll have to repurchase it, and I'll bet it won't be as inexpensive. 

Facebook (free) - Keep up with your friends with this iPhone application of Facebook. You can post to the "Wall" with this App and upload photos.  

Stanza (free) - Turn your iPhone into a Kindle. This free program allows you to download and then read a great many public domain works including the Bible and works of Shakespeare. There are other book reading programs available, but they cost $.99 or more for downloads. 

iPint (free) - How about passing me a beer? This game program makes use of the vertical and horizontal sensors on the iPhone so that you can "slide" a pint of beer to your friend at the end of the bar. When he/she gets the beer, you can toast.