Dear Mr. Jobs: Please May I Have A Mac On A Stick?Dear Mr. Jobs: Please May I Have A Mac On A Stick?

For Mac users traveling without a laptop, it's a cold and lonely world out there. You're forced to rely on the kindness of others for access to computers, and those others -- hotel business centers, family members -- are usually running Windows. Wouldn't it be great if you could run a cut-down version of Mac OS X on a USB drive? Then you could have access to your favorite Mac programs wherever you go.

I recently spent eight days traveling without a laptop and decided to invest in a keychain drive. I got myself a SanDisk Cruzer 8-Gbyte drive, for about $80. I could have made do with a lot less memory -- and spent a lot less -- but, darn it, I'm an American! This is the land of supersizing and little old ladies who drive Hummers to pick up their prescriptions! I want more! MOAR! MOAR MOAR!

The Cruzer runs software called U3, which lets you run your favorite applications directly off the drive. Sweet! And yet, not as sweet as it could be, because I've been using a Mac as my primary computer since February, so my favorite Windows applications aren't my favorite applications any more.

When I was done traveling, and fiddling with my Cruzer drive, I returned to work and talked to Moka5, which makes LivePC, software you can put on any USB drive and allow it to run Windows or Linux in a virtual machine. The virtual machine will run on any PC running Windows, Linux, or (starting next week at Macworld Expo) the Mac.

LivePC runs on any USB storage device: A thumb drive, spinning media, or iPod.

But, while you can run LivePC on a Mac, you can't run Mac OS X on the LivePC, because Apple's licensing terms forbid running desktop Mac OS on a virtual machine, John Whaley, founder and principal engineer for Moka5, told me.

This got me thinking: Why can't you run Mac OS X on a USB drive? If you could do that, you could sit down at the PC in your hotel business center, plug in your thumb drive, and magically transform the crappy Windows XP PC into a shiny Mac running your favorite software and documents.

Mac-on-a-stick wouldn't be full-blown OS X, but a cut-down version that runs in a couple of gigabytes. Likewise, it probably wouldn't be able to run the most sophisticated Mac apps, but simple stuff like Mail and iCal would run fine.

If Apple can get Mac OSX running on the iPhone and iPod Touch, surely they can run it on a USB stick?

Unfortunately, this proposal runs counter to the Apple philosophy in several ways. Apple doesn't make cheap PCs. Its systems are competitive in price-performance to midrange or high-end PCs running Windows, but they're intentionally not going after the sub-$1,000 market. In a Q&A with the press this summer, Steve Jobs said low-cost PCs are simply not in Apple's DNA. "We can't ship junk," he said.

And there's no PC more low-cost than a thumb drive, it's a little bit of plastic you pick up at Wal-Mart next to the T-shirts and the beef jerky display. (That's literally true; I bought my thumb drive at Wal-Mart.)(OK, the part about the T-shirt and the beef jerky was made up -- I found it in the electronics section.)

Likewise, Apple doesn't license its operating system to other hardware vendors. Apple tried it about a decade ago, it didn't work. If you could run Mac OS X on a thumb drive, you could also run it on a Dell or Hewlett-Packard PC.

One of the reasons Apple doesn't ship low-cost PCs and doesn't license its OS is because Apple wants to maintain tight control over hardware-software integration to keep their computers stable and minimize bugs. I applaud that sentiment, and I'm not really interested in running Mac OS X on anything other than Macs -- but in this case, I'd like to make an exception, because it would just be so darn convenient to have my favorite Mac apps on my keychain when I travel, and be able to run them on a Windows PC. I don't think stability is an issue here; people can be educated to expect that the USB drive just won't work in all circumstances.

However, despite the undeniable usefulness of Mac-on-a-stick, I just don't see it happening.

One possible alternative: Apple plans in February to come out with a software development kit that will allow third-party application developers to write applications native to the iPhone. A third-party developer -- or Apple itself -- might develop an application that allows users to run Mac applications on the iPhone, when the iPhone is connected to a PC running the Mac or Windows.

However, don't count on it. The Apple SDK announcement raises a lot more questions than it answers. Apple says it wants to control the applications developed for the iPhone, so they can protect users from security threats. How tight will that control be? Will Apple decide it needs to "protect" users from doing things that run contrary to Apple's business model? And will the SDK support applications for the iPod Touch?

Still, we can at least hope that our favorite application vendors will develop versions that run on the iPhone, and possibly the iPod Touch.

Meanwhile, I've been exploring the interesting world of portable software. U3, which is bundled with the SanDisk stick, runs selected Windows applications. Many other Windows apps will run from a USB drive as well. I tried the stick out with my favorite Windows text editor, NoteTab Pro and it works great.

Lifehacker has a list of Top 10 USB thumb drive tools, including tools for booting a separate operating system, encrypting your drive, speeding up or locking down Vista, and quick-launching your workspace.

Our former columnist Fred Langa wrote a step-by-step guide to putting Windows XP on a USB drive.

MakeUseOf.com has a list of 100 portable apps for a USB drive

And PortableApps.com is the Internet center for portable software, including Portable Firefox, the AbiWord free Microsoft Word-compatible word-processor, and OpenOffice.org

You can even have that Mac-on-a-stick I was talking about -- if you're willing to settle for System 7.1, which came out in 1991. I'll give that a whirl as soon as I put on my parachute pants and watch the new episode of Cheers.