This might only make sense in the US where we have only two serious political parties: Republicans and Democrats
Generally, the symbol of the Republicans is red elephant, the symbol of the Democrats is a blue donkey, but you can imagine other simple icons that represent your local political parties
in whatever country you may be in.
In the US, it is possible for corporations to make large cash donations to these parties. Often they give to both parties, deliberately to cause confusion, but they tend to give more to one party than they do to the other. Some people compile lists showing which companies are "Red" or "Blue."
I propose a guerrilla boycotting/buying campaign.
First: print small stickers with the logos of the party you do not like. Next affix these very small stickers near the door knob of the local branches of such corporations in your area. Now you and those who pay attention to your web site (which offers templates for printing stickers and a mapping application to make the work go faster) will know as they enter an establishment of it is red or blue.
It would be even better if the stickers could show a number (1-10) indicating the relative strength of support.
Better yet, to avoid the potential arrest that could result from stickers, and the potential for meddling by rouge sticker users. Create a PDA application with a simple look-up function.
Or perhaps banks could offer a service where they analyze your purchase for the month in your bank statement and indicate the degree of redness or blueness of your purchases. This would give people feedback on how well their boycotting/and selective buying was working. Or this could be an application that you download, and then feed the raw data form your electronic bank statement.
If corporations are going to buy in to our political system maybe we can fight back with smart capitalism.
I doubt many people would bother, but those who did could feel good about it at least.