Nearly all states have long recognized the need to protect their citizens from debt traps resulting from excessive interest rates, setting limits on such rates through usury laws.
However, due to the Commerce Clause, these restrictions are ignored by companies relocating in a state without such laws (particularly credit card issuers), as their actions with citizens outside that state is thus "interstate commerce." (http://bit.ly/6YoIAW)
States are thus left powerless, while lenders are encouraged to lend irresponsibly on promise of huge interest.
Establishing a national usury law, pegged sensibly to Fed rates or LIBOR, (including properly considering interest-like penalty charges such as late fees), would protect consumers and encourage responsible lending from the financial sector.