(It's right there under "2. Why did you make YubNub?")
So yes, it's slightly harder to use than a browser keyword, but it is more widely available.
The first five people to sign up under Free iPod account and complete an offer under my referal id will get a Gmail invite. I currently have five, but if I get more invites I'll update this page accordingly. Send me an email with the email address you used to sign up, or post a comment to this entry, and I'll send your Gmail in