Well, it's the flies from LA: DX, but I'm sure a more creative use could be interpreted =P
Quite pointless on it's own really, purely aesthetic, but you could use it as a movement pattern for a custom boss or something?

Requires the 'Run Script on Screen Init.' Flag checked
Code:
ffc script fly{
	void run(){
	int t = 0; int x; int y;
	this->X = (Rand(240)+8);
	this->Y = (Rand(160)+8);
		while(true){
			if(this->X < 8){
				x = (Rand(26)/80);
				y = (Rand(26)/80);
				if(Rand(2) == 1){y = y*-1;}
				this->Vx = x;
				this->Vy = y;
				t = 1;
			}
			if(this->X > 248){
				x = (Rand(26)/80);
				y = (Rand(26)/80);
				if(Rand(2) == 1){y = y*-1;}
				this->Vx = -x;
				this->Vy = y;
				t = 1;
			}
			if(this->Y < 8){
				x = (Rand(26)/80);
				y = (Rand(26)/80);
				if(Rand(2) == 1){x = x*-1;}
				this->Vx = x;
				this->Vy = y;
				t = 1;
			}
			if(this->Y > 168){
				x = (Rand(26)/80);
				y = (Rand(26)/80);
				if(Rand(2) == 1){x = x*-1;}
				this->Vx = x;
				this->Vy = -y;
				t = 1;
			}
			if(t==45){t = 0;}
			if(t == 0){
				x = (Rand(26)/80);
				y = (Rand(26)/80);
				if(Rand(2) == 1){x = x*-1;}
				if(Rand(2) == 1){y = y*-1;}
				this->Vx = x;
				this->Vy = y; 
			}
			t++;
		Waitframe();
		}
	}
}
It's also a bit hard-coded as is, but you could change the time limit it takes before changing direction or the speed limits on it's movement or whatever if you wanted.