One of the latest such offerings is the USB CardBus Adapter, from long-time Mac vendor Macally. The potential for misplacing the connector cable is certainly there, but leaving the card and cable perpetually connected easily resolves that, albeit with added bulk. Additionally, this two-piece configuration is a different approach from other USB PC cards that are a single, integrated unit. However, those types of cards may block the open PC card slot, so it may just be a matter of personal preference.
Installation is both straightforward and easy.
Simply install Apple's USB Card Support 1.3.5, insert the card into either the upper or lower card slot, plug in the devices and their respective drivers, and restart the PowerBook. According to the tiny, somewhat too concise manual, Macally doesn't recommend ejecting the card while the PowerBook is in sleep mode. Once the card has been ejected, Macally specifies waiting 10 seconds before reinserting it. All devices functioned as they were supposed to, despite repeated hot-swaps with the PowerBook on and in sleep mode. There was one instance where the keyboard power button didn't turn the PowerBook on or off, but restarting via the PowerBook's power button led to no further problems.