Well there are other uses too. Lets discus them in points first.
- Pull up or Pull down resistance. (also called passive pull up or pull down)
- Limiting the current in input signals also for impedance matching in amps.
Pull up or Pull down resistance
In general, a pull up or pull down is used to provide a reference to the input signal. Consider a circuit where the input is open(In case of switch intercaing with microcontroller), a pull up/down will either pull the voltage to Vcc or pull down to ground, hence avoiding floating voltages at the input of a gate.
Limiting the current in input signals
Limiting the input current is very important if you are playing only with voltage levels. Example, if you are reading some value with an ADC, we don't need much current. A series resistance in this case will help in limiting the current and avoid loading the source.
As in my previous post about caapcitor, I got a nice comment from one of my friends, talking about the filter. The decoupling capacitor in any circuit, includes the series resistance of the circuit and thus makes a cutoff frequency for a filter to block certainf frequencies. Now if we are aware of what to block, we can easily implemet RC filters to avoid noise.