If you must have a pong, Heiko Selber's honourable mention beats Piotr Dabrowski's hands down, in my opinion -- yours is pretty classy Piotr but I prefer the full field, myself (same reason I detest tablet-ized interfaces).
But I don't think the logo should go crazy on sideways references; hence I cannot vote for any of the other "presented" options. My top 6 are, therefore, #1, #7 and #9 from the accepted list, and Pocholo Peralta's, Erik Berglund's and Pete Mendoza's honourable mention entries.
* #1 refers to these polls, a strong feature of slashdot from so long ago that it might as well be the beginning.
* #7 has classic lines and is self-referential to its topic
* #9 is almost Matrix-y and ASCII-art-ish without being a 100% send-up of either
* I preferred Pocholo Peralta's logo over Sean Murphy's #31 because I view animated graphics, generally, as abominable. This works in the 15th anniversary theme tastefully and effectively.
* Erik Berglund's logo embodies slashdot's quirky take on everything -- give it a twist!
* I like Pete Mendoza's contribution for the same reason I prefer #7 to the ones to vote for. I'm disappointed that nobody used the default Slashdot logo font in the same way, actually.
I think I'd have to vote for #1, as much as anything because I can suffix my vote with
you insensitive clod...ank