You can tag or graffiti cars, walls, shopping centres,
corporate surfaces with antiwar slogans. With important
messages.

You can easily from your homecomputer send e-mail
messages including big files. When you and
1000 other people send e-mail messages including large files to selected corporate gangster or government elements their system will break down - at least for a period of time. There is no way their network could handle such an
amount of info - so it will break down their system.
You can easily repeat this again later.

You can also throw molotov cocktails through
corporate windows.

You can make sabotage and cause economic damage
to the warmachinery.

You can collect money and buy arms and ammunition and
arrange a media-spectacle in your city. Delivering
the ammo to the embassy of Iraq - you can be sure that
this will be broadcasted in the evening news.

You can use your imagination.
Unless you have become another comfortably numb.

You can. If you want.