You may remember choosing whether or not to let a few dollars of your tax return -- it used to be $1 -- be used to help finance candidates for President. The system is intended to help reduce corporate influence, and it may help less well known candidates get started. It all works by matching donations -- you and I can't just pick up money by pretending to run -- and limiting spending.
Frank LoBiondo and the new Congressional majority just voted to end public financing.
On the other hand, the truth is that system is collapsing so it's not an entirely bad vote. The public financing system made G. W. Bush President (since it limited Gore's spending, but Bush opted out) while Obama opted out entirely and was therefore able to run campaigns in more states. (He won in Indiana and picked up an electoral vote in Nebraska!) No major candidate will ever be limited by this system again.