i am sure you can pull at least 2 amps through them before them catching fire and easily half an amp safely.
I'm sure you can draw a lot more than 1/8 watt through an 1/8 watt resistor before it catches fire.
Typically manufacturers rate these wattages so that the resistor won't heat up much (if at all) when pulling its rated wattage. You can certainly pull more than the rated capacity through a resistor, I have many times. Presumably if you push through more than the resistor's rated capacity the resistor will wear out faster. (But this is similar to the argument about overclocking: supposedly overclocking will reduce the life of your processor; however, most people aren't going to care because they'll upgrade their computer before it would ever matter.)
Also, it definitely depends on the resistance value of the resistor. If you plug a 100 ohm resistor into the formula I had before, it can draw up to 35 mA according to the official spec.