We've all been there at some point, and there's the obvious - jumper cables.
Remember to take a jump from a battery that has a higher rating than yours, else you run the risk of two motorcycles that won't start after your attempts. The next obvious thing to do is to either remove the battery, get it charged and reinstall it, or replace it with a fully charged one. There are a few other things you can do if jumper cables aren't available, or you don't know how to remove your battery.
Note: if it is a large motorcycle (say over 400cc) do not attempt anything you read beyond this. If, however, you have a small motorcycle with a carburettor, here's exactly what you need to do: stick it in second, pull the clutch in, push the bike and release the clutch. As soon as it catches, pull the clutch in. If you have a helping hand, it is far safer to have one person sit on the motorcycle while the other pushes. Another trick that you can use for small motorcycles is putting them on the main stand – the same rules apply. Stick it in second, leave the ignition on and just give the rear wheel torque by pulling it in the correct direction. If you give it a hard enough tug, the bike should start.
There is one other condition under which a push-start will not achieve any results at all: if you have fuel injection on your motorcycle, turn the key over to the 'on' position and put your ear near the fuel tank. If you hear a noise, however weak, it means that the fuel pump is still working enough to send fuel to the engine, and you have a chance of the bike starting. Pull the fuses to the headlamp to keep it from taking any more juice away from the fuel pump and try the push start. If you turn your key to 'on' and hear nothing at all, then don't bother trying, your motorcycle won't start no matter how much you push it.
Revving the motorcycle to the redline will not make the battery charge faster – anything beyond 3000 rpm is a waste of fuel, so go for a 20-30 minute cruise to make sure the battery gets charged enough to crank the engine should you stall for any reason.