What's there to see at a Macworld Expo without Apple attending? Plenty, if you own an iPod, or at least have a collection of digital tunes stored on your computer - even if you don't run the Mac OS.

Apple chose to forgo this year's Macworld Expo here, unhappy with the decision to move the show from New York. But many third-party developers and software application vendors have made the trip further north. Among them: Several companies offering protective and decorative iPod cases, which seem to be at every other booth. Here's a rundown of some of the more interesting products on display that don't require you to own a Macintosh PC.

Let the music play

Roku is demonstrating its SoundBridge Network Music Players, which allow you to listen to your digital music collection throughout your house. Introduced in January but not shipping until the end of July, the Roku SoundBridge is available in two versions, the US$499 M2000 and the $249 M1000. Both are sleek silver-and-black devices with a thin display running across the front, although the M2000 is about twice the size of the M1000 and features a larger, easier-to-read display.

The Roku SoundBridge connects to your home network, either through Wi-Fi or wired Ethernet, to access your music library. It connects to your speakers with an RCA-to-mini audio cable, or to your stereo system using analogue RCA or digital optical or coax audio outputs.

The screen displays track names, and it includes a remote control for browsing through your music collection. The devices support MP3, WMA, AAC, AIFF, and WAV formats. At the Macworld Expo here, the company is announcing compatibility with Apple's iTunes music sharing features, for both Mac and Windows users.

Portable sound systems

Harman Multimedia, a division of Harman International Industries, is showing two new audio devices here. The JBL On Stage is a compact sound system for iPods and other digital audio players. The JBL On Tour, meanwhile, is a personal portable sound system.

The JBL On Tour, scheduled to ship in early August priced at $99, is a set of 6-watt portable speakers. When closed, the device is a smooth, slightly curved white and silver case, 7 inches long by 3.5 inches deep by 1.4 inches high. It weighs 12 ounces. The top slides open to reveal two small circular speakers. It features a stereo minijack connection, which connects to iPods, iPod Minis, MP3 players, portable CD players, desktops, and notebooks. It runs on four AAA batteries, or can be connected to a power outlet with its included AC adaptor.

The JBL On Stage is a doughnut-shaped set of 12-watt speakers for iPods, iPod Minis, and other MP3 players. It has a dock to connect to your iPod, and includes OnePoint iPod connectors to link the device to your PC to synchronize and charge your IPod. The On Stage is 7 inches in diameter and weighs 1 pound. Harman is not disclosing a price, but a company representative here says it will ship in September for less than $200.

Hit the road

Like many companies at Expo, Belkin is showing several iPod accessories. Many of Belkin's products, which include voice recorders, backup batteries, car power cords, iPod cases, and cassette adaptors for car stereos, have been around for some time.

But Belkin is showing a unique iPod accessory on the show floor: the TuneDok Car Holder.

This $30 device, introduced last year, lets you securely store your iPod in your car's cup holder. Its rubber base attaches to your holder with a suction cup; it has a flexible neck to support your music player, and a clip to keep your cables (such as those that connect to your cassette adapter or car charger) out of the way. A new version of the TuneDok Car Holder works with an iPod Mini. Belkin also makes a TuneDok Car Holder for Dell's DJ MP3 player.

Power pack

On board the iPod accessory train is Battery Technology Inc., also known as BTI. The company is showing the iPod Battery, its rechargeable battery pack for Apple's digital music players. Similar to Belkin's Backup Battery Pack, BTI's pack attaches to any iPod with a dock connector. Unlike Belkin's $70 device, however, BTI's $100 device works with the iPod Mini. The company promises 40 additional hours of playtime, and a representative at its booth here says tests have revealed more than 75 hours of battery runtime.

BTI's battery pack, introduced in May, adds a significant amount of weight to an iPod. The entire pack, including the AC adaptor to recharge it, weighs about a pound. The battery alone, when attached to the iPod without the AC adaptor, adds between a half-pound and three-quarters of a pound in weight. According to Apple's Web site, a 10GB iPod weighs 5.6 ounces, so the battery pack will more than double that.

Media management

Much of the software on display here is strictly for Mac OS users. But iView Multimedia is showing its recently launched iView MediaPro 2.5 for Windows.

The $199 application is designed for creative professionals who work in the film, video, photography, broadcast, or scientific fields. It allows you to manage your collection of digital images, video, audio, illustrations, and more, by creating media "catalogs." Version 2.5 features enhanced tools for searching through massive collections of digital media, and for creating QuickTime slide shows and movies.