I go for claymores. In BF2 they saved my ass more times then I can count. Once I saw some guy swimming towards my ship/spawn point so I claymored the ladder he would have to climb up to get into the ship. It was a lan game so it was funny to hear the guy curse from across the room when he died.
Later on the same map, I was on the crane sniping people in the other base. People started to get pissed at me because they said I was "camping" to which I retorted "Its called sniping! Get it right!" That comment led me to become the number one target in the game. Now before I was targeted by everyone, I place a few claymores on the only way onto the crane. A few died on the ladder and the only one left was one in the well that couldn't be seen from the ground. From across the room I hear "Damn it! We need to take him out. Who is close to that crane?" "I am, but all I have is a knife left." "I'm looking right at him, you can get him if you hurry." Now I knew I was safe, so I didn't want ruin the surprise. About 30 seconds later I hear a boom and a note that I got a kill along with a stream of curses from across the room. There is more that happened that day, but I'll leave that for another time.