For the fourth year in a row, sales of PDAs are down. At least that's true when looking at traditional PDAs: handheld computing devices, typically running Palm or Mobile Windows and lacking phones.

To a large extent, PDAs are being replaced by mobile phones, whether traditional cell phones or more powerful so-called smartphones. Any of these let users store address books, calendars, and task lists, which is what most PDA users do.

If you already have a mobile phone you're happy with but want more capabilities, Apple has recently provided a look at a device with the potential for picking up where the traditional PDA left off. No, not the company's massively-hyped iPhone (which is still not available in Canada as I write).

Available locally, but not getting anywhere near the attention, is the company's newest entry into its iPod media player product lineup, the iPod touch. Available in 8 GB (US$299) and 16 GB (US$399) models, the touch is in many ways a sibling of the iPhone. It shares that model's large high resolution colour touch screen, its innovative and easy to use interface, and a similar design, packed into an even slimmer and lighter housing. (Unfortunately, in common with other iPods, it has an easily scratched shiny steel back, rather than the iPhone's brushed metal case.)

With traditional 8 GB iPod nano models listing for US$199, it's natural to wonder what makes the extra expense worthwhile. Some of the extra value comes from the large LCD display, making it much easier to watch video content on the touch. But the biggest bonus is that the touch (like the iPhone) has built-in WiFi. As a result, when near a standard wireless network, iPod touch users have web browser access. I use Google's services for email and for storing my contact list and calendar; that means full access to those services. Alternatively, it can be set to sync with calendar and address book applications stored on the user's computer, making them always available.

And as with the iPhone, there's a version of its Safari browser on the touch, delivering the best web interface of any mobile device - not a mini-browser that can only go to a limited number of sites as on many cell phones, and not a "mobile" browser, a la Blackberry, Treo, and other smartphones that displays webpages one column at a time. Safari displays a tiny view of the entire webpage, with just a few easily-learned finger movements making it easy to zoom and scroll.

Lacking any physical keys, the touch pops up a virtual keyboard whenever text input is needed, like when you click in the browser's address or search fields. The virtual keyboard is easy to use, the equal of the mini-keyboards built into typical smartphones.

Missing is support for Flash animations and other streaming audio or video. That's surprising, since the touch and iPhone come with dedicated YouTube applications, which do a very good job of displaying these popular Flash-based videos. (And which allow users to access any YouTube content, unlike the limited access offered by some mobile providers).

Unlike the iPhone, the iPod touch lacks a built-in camera, sound input, a speaker, and the ability to use it as a portable hard drive. As with the iPhone, Apple is busily engaged in battles to limit third-party abilities to add applications. This battle has swung back and forth in the months since both products were released; hackers announce methods to "jailbreak" the devices, opening them up to add-on software. Soon after, Apple releases a firmware upgrade that locks the devices back up and disables the additional software. A few days or weeks later, developers release a new technique to open the devices back up. Currently I'm unable to load additional applications on mine, but I've seen software ranging from ebook readers to dictionaries to utilities to use it as a carpenter's level or a flashlight.

Eventually, I suspect Apple will give up the fight, opening the iPod touch and iPhone platforms. Even before that happens, with its already excellent WiFi Internet access, music and video media player functions, and calendar and contact capabilities, there's a business case for making the new iPod your next PDA.

See Low End Mac's Best iPod touch Prices for the best current prices on Apple's iPod touch.

This column originally appeared in Business in Vancouver. It is republished here with permission.