starting problem + daily driver = HELP!!!

When I turn the key, all I hear is the clicking from the solenoid. I bypassed the solenoid, and the starter turns a couple times VERY slowly and then stops. Here are the things I have checked today...

Battery - Fully charged, 13.1 volts, holding its charge fine
Starter - Bench tested, worked perfectly
Battery cables - New condition, no corrosion on terminals
Solenoid to starter cable - same as above

What am I missing here?
 
Thanks for the info guys. I just assumed the battery was fine when it charged and tested at the right voltage. Anyway, I took the battery to Pepboys, they tested it, and it had a bad cell. So I got my free replacement, put it in, and no more problems! I probably tested everything else in the starting system. Oh well, at least I learned some things.