I would like to suggest the following (not that I'll be painting them on any billboards in the near future!):
Download Free Music - what's radical about downloading the music if it's free? How about: Download more music!
Support the Iraqi People - how about 'Solidarity with Iraq' (The notion of international solidarity needs to be reasserted)
Kill Fascists In Iraq - maybe jst Smash Fascism or 'Give fascism the purple finger'
It's Right To Rebel
www.lastsuperpower.net
Neither Labor nor Liberal - I agree with the comments above by youngmarxist and arthur.
BUT, one new one could be: The future is bright. (Remember the dude who used to go around Sydney writing 'Eternity' everywhere? A pity we can't do that with 'The future is bright').
Also, off the top of my head, as a "sixties person" (no, not because i'm heading for my sixties!!), I reckon John Lennon's 'Imagine' has some significance: Imagine no religion and Imagine there's no countries.
Even plain old Rock on! sounds leftwing these gloomy days,
Barry