Time to replace that receptacle. The sparks are resulting from a poor connection between the plug blades and the contacts inside the receptacle. This also poses a fire risk -- a poor connnection can cause high-resistance - which can generate enough heat to start a fire!

A new receptacle is less than $2.00 and takes all of 10 minutes to replace. The basic steps are-
-turn off the power AT THE BREAKER!
-unscrew and remove the cover plate
-unscrew and remove the receptacle
-disconnect the wires from the old receptacle and reconnect them to the new receptacle - black wire to brass screws and white wire to silver screws
-if not using the screw terminals, turn them in all the way before reinstalling the new receptacle (reduces the chance of shorting against the side of the box)
-reinsert and screw in the new receptacle
-replace the cover plate
-turn the breaker back on

Before starting, plug in a light, radio, etc to the bad receptacle and turn it on, then start flipping breakers till your test device turns off. If this is a "switched receptacle" (one half is always on and the other half is controlled by a switch), it's possible that the switched side is controlled by a different breaker - test both outlets on the receptacle before removing the cover plate to be sure it's really dead.

If the wires on the existing receptacle are "back-wired" (poked into small holes in the back of the receptacle, instead of the screw terminals on the sides), you'll need a VERY small screwdriver to insert into the release holes to release the wires. If you don't have a small enough screwdriver, you can either use a stiff piece of wire - 14ga or a wire shirt hanger should do - OR - use a medium screwdriver to twist and pry the release hole until the whole side of the receptacle breaks away (the receptacle is trash anyway).

Connect the wires to the new receptacle in the same way that they were attached to the old (either screw terminals or back-wired), and you won't have to mess with cutting/stripping/bending the wires - simply remove from the old receptacle and reattach to the new in the same way.