One of the things that has always bugged me about Apple laptops is the fact that Apple always left the PCMCIA slot off their smallest laptop (12" Powerbook) and now leaves the ExpressCard slot off of their MacBook Air (along with firewire, ethernet, ahh... don't get me started!)Even the 13" MacBook is missing the ExpressCard slot (just like the earlier siblings the 12" and 14" iBooks were missing the older-style PCMCIA slots.) Why this bothers me is because both the ExpressCard and PCMCIA were a very flexible interface and therefore used for many different uses. I have and ExpressCard EVDO modem, an ExpressCard compact flash card reader, a SATA ExpressCard... and the list goes on. But without the slot, these cards are unusable on MacBooks, or iBooks and certainly on the MacBook Air.
If you find yourself in this predicament, take a look at Synchrotech. They make a wide range of adapters that will allow you to use ExpressCards and PCMCIA cards on laptops (or desktop Macs, for that matter) through your USB port or through an existing slot, for example, you can use a PCMCIA card with their ExpressCard to PCMCIA adapter or like I have done above in the photo above, I am using their USB2 to ExpressCard adapter for my EVDO modem that I share between my MacBook and my MacBook Pro.
I know that it is not a very safe looking connection in the photo, with that thing hanging way out to the side, but it made for a decent photo, eh? What I normally do is use a USB2 extension cable to put the modem closer to the nearest window to boost my signal and to avoid having it hang off the side of the laptop like that. It doesn't impact the speed at all when you use a USB cable, either.
Ultimately, Synchrotech has created some cool solutions that makes me glad to use a Mac and allows me to exist without the ExpressCard slot on every machine.
Oh, and the adapters I've used all seem to be compatible with 10.4 or 10.5
