I use it for my comments so blog spambots cannot directly hit my mt-comments.cgi without knowing the key. Since the key is just a variable hidden in my SWF, and no blogspammer has yet written a Perl spambot to rip open my SWF, introspect the variables, and thus carry this key to my server… I remain protected from blog spam.
I’ve noticed over the past 3 years, Captcha’s have gotten more and more elaborate. The one used when signing up for an Microsoft Passport, used in Windows Messenger, is nigh unreadable (even after 5 page refreshes), and I’ve got 20/20 vision.
Aral’s using it to confirm a human is in fact making an edit to the Wiki just by a simple animation (a lot more readable than the Salvador Dali’s I’ve seen generated). Smart thinking, Aral! Another great niche use of Flash.