Though Eye-Fi's Secure Digital (SD) card has been out there for a couple of years, it's worth revisiting--just because it works. And it's not be a bad idea as a holiday gift for any digital camera owner.

Eye-Fi allows the transfer of photos from existing digital cameras wirelessly. A nice piece of inexpensive technology that has worked well for me.

The Eye-Fi card replaces a standard SD card.

Eye-Fi SD cards come in 4GB and 8GB capacities and, after a relatively painless setup, do away with USB cables and the task of inserting/removing of SD cards.

Because I own a couple of MacBook Airs, this technology makes a difference. My first- and second-generation Airs have no SD card slots and just one always-occupied USB port--one of the few downsides to an otherwise superb ultraportable laptop. So, this is a feature I need--though not to the point where I would want to limit my camera purchases to Wi-Fi-enabled models, like the Kodak EasyShare One--that was available a few years back--or the Sony Cyber-shot DSC-G3, among other cameras.

It's really just a matter of replacing your current SD card with the Eye-Fi card and having an in-home Wi-Fi router, which many people do these days.

Setup involves inserting a USB adapter into your system (the adapter is used only once at setup, after that everything is wireless), then confirming your Wi-Fi router information, and finally choosing where you want the photos to be stored on your laptop. There is a background application that handles the automatic transfers when you take photos.

Configuring the card requires you sign up for the Eye-Fi center. Setting up an Eye-Fi account did not go swimmingly when I set up the card--asking me to set up an account multiple times--but the Eye-Fi database seems--for now at least--to have resolved that hiccup.

I've been using Eye-Fi with my Kodak M580 and MacBook Air. So far, the card has done what it claims. As soon as you snap a picture, the photo is automatically sent to your PC over your home's Wi-Fi network. For me, it has been almost instantaneous.

And the Eye-Fi Center software also allows you to set up multiple networks. So, for example, I have Eye-Fi set up for my home Wi-Fi network and my mobile Verizon MiFi network (the latter is a credit card-size router that provides 3G connections for up to five devices.)

The 4GB version (which I have) is $39.99 at Best Buy, while the 8GB card is $99.99.