The only thing I've missed since I switched from my old reliable Treo 650 to my iPhone is an onboard password / information management tool. On the Treo 650, I used a utility program called SplashID, which was great for remembering hundreds of sets of application and server credentials.
(I mentioned that I was trying SplashID on Operation Gadget back in 2005, but never wrote a full review. You can find a good SplashID review on Everything Treo.)
I had concluded that I would have to wait for one to be released after the iPhone SDK is made available until I heard about Yojimbo from Bare Bones Software. Yojimbo is an information organizer for MacOS X that can be used for password management. I'm planning to get a Mac mini to go with my iPhone in a week or two, so this software will be a step in the right direction.
Yojimbo integrates with .Mac for synchronization services. It also intregrates with a third party service called Webjimbo that provides glue between the Yojimbo application on your Mac and a website that's browser and iPhone friendly.
Yojimbo does a lot more than just manage passwords. You can also use it to manage snippets of text, images, PDFs, and similar stuff. It also integrates well with Spotlight, so it makes a lot of sense as a note taking application for people who are heavily in to the Mac platform.
Macworld did a good review of Yojimbo back in March 2006. That probably needs to be updated, but it still provides some good background on the application.
The cost of doing this is $39 for Yojimbo (or $69 for the Yojimbo Family Pack) and $29.95 for Webjimbo. I don't think that a .Mac account is required in order to use Webjimbo, but for other synchronization services on the Mac platform, a $99 per year subscription to .Mac is required.
This sounds like a lot of money to spend to keep your passwords organized and at your fingertips. However, it is a password management solution that's available to iPhone users today. I'm definitely planning to give Yojimbo a try when I get the rest of the pieces of my new computing life assembled.