So, one car barely works while the other won't start at all (2006 civic). Here's what I did:
Tried charging the battery about 10 mins by hooking jumping with the other car - got the engine to turn over 2-3 times instead of once
Figured I'd go and get the battery tested to be sure it was the problem. Had the Fleet Farm guy test it and he said it was fine.
We do have those obnoxious computer chipped keys which give us problems from time to time. The metal key is busted off the black pad and sometimes that can make it difficult to start the car, but the car seems to die after turning over 3 times or so. If it was the key problem, usually it turns over fine and then just stops.

Ideas as to what this could be?

 

Have you had your starter tested?

Do you hear the fuel pump priming when the key is placed in the ignition?

 

Measure voltage at the battery, on the lead posts that are part of the battery. If it drops below 9 volts while trying to start, the battery is either run down or defective. With the engine running but everything else turned off, it should be more than 13.5 volts. If not, the charging system isn't working.