I was going to say the the only ones that are any good are the ones that actually stick to the format and don't use a word other than "Google." Doing something like "Boobies" is completely pointless because it's not what the custom Google logos are about.
But, I did like the Smeagol one, especially because the shadow it was casting said "Gollum." Ok, and the Festivus one cracked me up - but not because it has anything to do with Google. Jerry Stiller Just does that to me and I was quite a Seinfeld fan. Haha.
Bruno