A debtors' strike is about using the power that debt gives to people to demand concessions.
There are, however, obvious difficulties. To begin with, the stigma that debt holds must be overcome. The idea of refusing to repay a loan seems offensive. If you sign a contract, it's your moral - not to mention legal - duty to pay it back. However, this misses the fact that debt is a political, and not a personal, issue.
Climbing private indebtedness is the outcome of a deliberate strategy on the part of banks and a wilful impotence on the part of government. Banks developed, sold, and lobbied against the regulation of corrosive debt instruments. They cannot, then, demand that the rest of the population bleed so they can maintain their practises. When the creditor-debtor relation is seen properly, as a socio-economic arrangement, negotiation becomes a fact, as well as an economic necessity.
The next problem is building a movement big enough. A one-man debt strike is as useless as a one-man labour strike, but the quest for a mass debt strike may actually be more plausible. Britain's service economy has fragmented the workforce as powerfully as the manufacturing economy once harnessed it; it's only across public sector unions where there is any coherence. Debtors, however, are much more concentrated. Personal finance is dominated by the five big high-street banks, and student loans even belong to a single company.
The most significant issue, though, is that in the era of securitised finance, the debts of one bank are the assets of another. Because of that, forcing a debt write-down could well throw a pension fund into trouble. Yet that need not be a bad thing. It would shine a torch on the murky behaviour of institutional investors who serve themselves far more effectively than they do their savers. It would also force governments into a position where they have to bail people out before banks. Successive governments have used Quantitative Easing to gift cash to the banks; the same strategy could be used for restoring people's pensions instead.