You may not have heard of this "iPhone" thing. It's somewhat obscure, with a vanishingly small share of the "smart phone" market, and it has an expensive data plan, but it is still useful. And it is even more useful now that Apple has introduced the latest version of the software, one that allows people to write legitimate apps for the device.

While there are lots of things you can do on the iPhone, I thought I'd highlight a few of the more interesting apps for investors. Feel free to add more in comments.

You can find all these apps on ITunes, or by going to the App Store from any iPhone running the 2.0 version of Apple's core software.

Feel free to add more to the list, violently disagree, or recite Vogon poetry in the comments.

Peak oil guy Matt Simmons -- despite sounding particularly apocalyptic -- makes a good point, and echoes one I made here earlier: At what point does a decline in oil price become a bigger issue than an oil price advance? So long as people think oil is set to collapse, investments that would be made, if we knew there was a price floor in place, will not be made.

I like to think of this as the oil bubble trouble bubble. It's the cancerous growth in the number of people thinking there is an oil bubble that's in trouble.

According to the Times of London -- in a very thinly-sourced story today -- Treasury Secretary Paulson is considering (or is that planning?) a $15-billion Federal Government cash injection into troubled U.S. mortgage firms Freddie Mac and Fannie Mae. The supposed plan would involve a new class of shares, almost certainly preferreds, and would hugely dilute existing shareholders. The firms would also get access to the Fed's reserve window under the plan.

This story is so thinly sourced that I was initially hesitant to post it, to be frank. These are skittish and perilous times, and no unnamed person is even quoted indirectly in the article, let alone directly. In many ways it sounds like an echo chamber version of what was discussed all day Friday by the chattering class.

That makes it hard to know what to make of it. Are we just hearing a cross-Atlantic repeat of what was discussed Friday, or is this story sourced sufficiently well so as to make it anything other than a stupid, contagious and dangerous rumor?