You've seen the Blogger Code, the Geek Code, and all of the other codes, but how about the ODP code? Yep, we have one now, and here's mine:
<ODP ver="1.0" code=" E++ F++++ D+++ X* N++ G Q++ Lo A+ H+ W- O+ B T+++ I---">
I'll let you decide what it means until someone writes a decoder. And yes, I imagine it is XML-compatible.
Oh yeah, and I've updated my Blogger Code too, since I've been blogging for more than a year now.

I’m surprised at you, Neil… I thought that by now you’d have included a link to my ODP Sig Code Decoder ( http://dmoz.theblob.org/dmoz/odpcode.cgi ) by now…
Not to worry, I’ve done it for you. :)
Oh dear, how embarrassing - this was my idea and I didn’t even know about it! :(