My try:
1/The improved road system did little to decrease the accident rate.
This sentence means the improved road system didn't do much to decrease the accident rate. Also we can say that the accident rate wasn't decreased much despite the improved road system or we can say that the accident rate was almost same despite the improved road system.
2/ BOGOTA, Colombia - Hugo Chavez, once a key mediator in securing hostage releases from Colombian rebels, could do little more than phone congratulations to President Alvaro Uribe after this week's bold rescue.
This sentence I sense that the writer is a bit dissappointed by the endeavours by Hugo Chavez. He/she says that he could try to to do more things, he could work more, he could change more things than just to phone to President A.U. to congratulate him.
I hope you I can help you with at least one of my sentences.