AOL gets it right, sort of.
After posting examples of access-obstructing captcha’s from the major search players Google, Yahoo and MSN, I was very happy to notice that AOL has the right idea.
I went to AOL to register a screen name for pathetic reasons, namely, my fantasy football league is moving to AOL, instead of CBS Sportsline. Why? It’s cheaper, as in "free" cheaper. Now I have to learn to use another website for this futile social custom of playing fantasy football.
Anyway, I had to get an AOL screen name. After all of the typical registration "stuff", I was happy to see two links on the captcha security measure; "What is this?" and "Can't see this image?". Very nice, AOL. Way to go.

In clicking the "Can’t see this Image?" link, the user is then presented with a new window that plays an audio version of the captcha.

The user is able to play the audio version three times before it gives an error message for exceeding the number of plays.
I have to say that this was great, as it is the first alternative I've seen in the search space. Granted, AOL is more than a search engine, and people like to kick them around, but I was impressed at the effort.
Now, for the bad news:
It didn’t work for me in FireFox, but I think it was a FireFox issue. The audio uses Apple QuickTime in order to play, however something doesn’t seem to be working correctly in my FireFox extensions. It kept telling me that I needed to download the QuickTime Plug-in. I’ve done that and I can view embedded QT files on other sites, but not here. I’ve noticed this in a few other cases, so anyone who can help me understand why this QT FireFox plug-in doesn’t always work will have my gratitude. Because of the plug-in, I was unable to play the file in FireFox.
Opera was a similar experience, except that it was a Media Player error. I checked through my setup information - my version of Opera isn’t full of additional programs, plug-ins and the like, so I was very surprised that it would not work in the basic Opera set-up.
Using it in IE was just a pain, mainly for their security measures. I was given two POP-up notifications. One that I was leaving a secure connection (the AIM registration), and the other that I was going to view over a secure connection. That doesn’t make sense to me. It’s like telling someone that the door will be open when you open the door - slightly redundant.
Other than those IE security windows clouding my experience, it went well. I would have liked to have known up front that I could only play the file three times, but I suppose you can always make the user go back and do it again (sarcasm added).
Hopefully, this is the start of search engines starting to recognize that accessibility needs to be a consideration of their registrations, as they are not allowing users to access many of their products and applications. It’s not without its bugs, but at least AOL made the effort.