For truly HUGE projects (people will cringe) I use the garden hose. Bring it inside, stick it in the tank, go back outside and turn it on. Then unscrew the faucet end of the hose and put the end of the hose into the flower bed. VIOLA. Empty tank in no time flat.
I learned this trick from emptying hot tubs and pools... works on big tanks too.
It may seem obvious to some of us, but from reading a few threads around here, it seems that a lot of people don't understand the basic physics of a siphon. When one has a solid column of water (think of a drinking straw, filled up) water can move in either direction, depending on which end of the column is lower. So, by filling the column (by turning on the faucet, or filling your siphon and holding your thumb over the end, or by sucking on one end of the siphon tube) and then making sure that the place you want the water to GO is lower than the place you want your water to come from, you can use gravity to do your work. Even if you fill up the siphon by moving water in one direction (say, into your tank) but then STOP sending water down the hose, as long as the water column is whole, it will begin to pull water back in the direction of the lowest end of the hose.
The python, however, uses venturi action to overcome this obstacle, which is why you would continue to run the water if your sink is higher than your fish tank. Hope this clears up some of the questions that people seem to keep asking.
Best of luck!