I like the slogan as it is personally, but now that you made the suggestion, it MUST change (just on principle).
Other's suggestions that i liked-
Mopsicle had a good point about the power and oppurtunity NG has given to otherwise anonymous artists. Saeadeb's idea made me think. make a new logo as well with a golden N ( or NG) and have "Over 10 million corrupted", a la the McDOnalds logo. lol. dosdragos' "If there ever was a line, Newgrounds has crossed it" was a good one too. rockymike's made me think "all the mindless drivel of television, and more." "breaking new grounds" was good. i hate everything else to do with the saying, but Money_is_Cool's *NG:All your eyes R belong to us" would work ( i feel so dirty). 76spidey's If you Flash it, We will watch" was kinda silly, but it made me chuckle the way the first one did. Ditto hyper_goat's "Newgrounds: We flash you for free!"
As for me-
Where the anonymous artist comes to shine.
Make it yours.
Showcase YOUR talent.
For the people.