A one of these might be more handy,
http://seventransistorlabs.com/Fuse/It doesn't provide any more than gross current limiting (around 100A surge), but it does limit the energy delivered into a fault. It's fast enough that you can build a circuit that accidentally explodes itself on a larger power supply, and have it turned off before damage is actually done to the transistors.
The one downside is, because it's so fast, you can't use much capacitance on the load, following the fuse. This can be addressed by precharging it with a current-limiting resistor.
For active current limiting, a circuit like this might be more handy:
You might want to complement everything (i.e., NMOS --> PMOS, PNP --> NPN, diodes reversed..) to use it on a positive supply, so your R_L (load) can be ground referenced.
As shown, the dropout is VREF + I_L * Rds(on). For VREF = 100mV, R1 = 0.047ohm gives 2.1A limit. It should be a pretty flat current source, once it's out of dropout. From a 12V source, the MOSFET will dissipate a maximum 25W when the load is shorted, so use a large heatsink. (IRF540 would be fine here, or 9540 for PMOS.)
Tim