What does the Occupy Movement want? Well, they could do worse than adopt this as their core unifying demand. It articulates what seems to be a strong universal complaint in the movement—that both major parties and government are completely controlled by financial and business elites, primarily though the campaign finance process.
The demand wrong-foots adversaries because "free and fair elections" is a universal demand of politically powerless peoples everywhere and is a central tenet of US foreign policy. Entrenched interests will find it hard to argue against this demand without clashing with America's cherished democratic mythology.
The Occupy Movement is being emulated throughout the world, and the demand for free and fair elections will tend to unify the movement internationally and reinforce its legitimacy.
Some of those (many in the Tea Party, for example,) who blame government for America's fiscal, unemployment, and declining wealth problems may be recruited to the Occupy Movement by the insight that government is bad because it is being manipulated by Big Money puppet masters.
This demand is actionable—it could be met by a Constitutional Amendment undoing Citizens United, for example.
Without this fundamental political reform coming first it is unlikely that other specific economic goals (such as tax policy, banking regulation, job creation, debtor assistance) can be achieved.
It would make the Occupy Movement more difficult to co-opt by a political party, labor unions, or other existing interest groups because they are invested in the present system.
The demand is a short declarative ideological statement of the sort that every movement needs. It avoids a laundry list of disparate special interest demands that would inevitably sound like a party platform and would rarely be read or remembered.
The demand lends itself to derivative formulations more suitable for signs and bumper stickers:
"Money out of politics."
"Government not for sale."
"Democracy, not plutocracy."