History records two ways of confronting popular injustice. One is through the intervening force of some central authority; the other, by undermining injustice in a way that makes it unpopular.
For our purposes, we might compare the federal authority of the United States to the moral authority of the abolitionist movement; or we might think of the military force of Allied troops during World War II versus whatever disparate groups might have derailed Nazi aspirations had they been sufficiently organized to do so -- the German Communist Party, for example, amongst a myriad of others. History recorded is always the history of possibilities not met.
The popular aspect of consumerism has to be acknowledged. The fact that people form attachments to material things can't animate an indictment of consumerism, because people form attachments to material things as part and parcel of being human and existing in the world. Consumerism merely places this consideration ahead of all others, and in doing so, deflects attention away from moral concerns that accompany it as a system. These include questions about the investment, production, and distribution processes of commodities; not to mention what portions of human experience -- like identity "branding," "ghetto" culture, and women's sexuality, for example -- will be subsequently commodified. The totalizing impulse of capital towards indefinite expansion suggests there is no realm it won't try to assimilate into itself.
Two significant contradictions within consumerism arise from its relation to the past, as well as its claims to a better future. Because consumerism, being an advanced-stage of capitalism, can only see as far the short-term, it is undermined by larger questions about life which, paradoxically, still remain in the broad realm of "religion" given the comparable limitations of present-day science. This is why a language of resistance to consumerism can more often be heard in the conservative church than even amongst secular progressives, whom consumerism identifies as most vulnerable in their youth. If you want a personal model of resistance to consumerism, you have only to think of the elderly church-goer as your inspiration!
For most of us, the contradiction we might exploit relates to how we participate in consumption, as well as to what degree. This may be less about resistance per se as it is about adding to the natural momentum of capital toward markets that it can't sustain. The "greenwashing" and "corporate social responsibility" movements stand as truly comical attempts by capital to promote itself as the solution to its own internal logic -- and anyone can tell you just how far Beyond Petroleum we have come, now that the Gulf of Mexico will let you swim in it. These initiatives deserve to be pushed to their natural conclusions, which should never be anything less than the public expropriation of all critical social wealth from private hands. But this will require individuals whose commitment to social and environmental justice is not sated by green labels on the products they buy, but which demands a market in "social goods" that capital cannot provide.
Something we learn from Marx is that ideas constitute a material force in history, and those of us contributing to culture through the relatively new, relatively open networking technologies should not discount these efforts on the basis that they aren't happening at traditional sites of resistance, like the picket line or capitol steps. While I think clickity-clacking in the comfort of one's domicile hardly constitutes a heroic act, it is an open question in my mind the degree to which it doesn't have the potential to be a more effective one as compared with marching down the street, being pummeled in some inscrutable confrontation with the state. There is a time and a place for such things, but I don't think they can be justly described as "the weekend."
Insofar as we are a long way off from even the kind of "change" that Obama supporters hoped to see through a "renewed engagement with the political process," concepts and understanding will have to change first. Only when conditions are favorably established can we hope to sustain a movement in the direction that we want to go, and in a way that people will actually want to be a part of. This will mean yielding to that place where most of us already are, in order to reframe the experience. In the context of consumerism, this means strategic participation within the patterns of consumption in order to undermine and eventually transcend them.