How many wires are at the lamp, 2 or 4.
And while we're at it, lets try to find a way to simplify this...
First of all, a light is typically provided electricity in on of two ways:
1. Switch - Black/White constant power goes to a switch box. In the switch box, the black goes through the switch. The switched black hot and the white neutral then go to the light to supply switched power.
2. Switch Loop - Black/White constant power goes to the light box. The *********** is connected to the white for the light. But the black power is connected to a white that goes to a switch. The black coming back from the switch is then connected to black for the light. When a switch loop is done this way, the white between the light and switch is actually now a constant hot and is supposed to have a black piece of tape wrapped around it to remark it from a neutral to a hot.
Not a three way switch is typically wired up the same general way (power to the switch, switch power to the light... OR power to the light, with a switch loop for the hot). The difference is that rather than just one switch, there are two switches that are connected together via travelers (the NON-Common screw terminals). Three wires are used to connect the two three way switches together, two for the two travellers, and one for the additional wire. So if you think of two three-way switches as a single unit, externally, you simply have two terminals for your hot to run through (these are the two common terminals, one on each 3-way) and internally, you have two wires that connect the two travelers, plus a third wire to account for the fact the two parts of the switch are in two boxes.
So with a 3-way, you can set it up as a switched hot or a switch loop.
If it's a switched hot, then your constant hot goes to one common terminal, the black and red of your 14/3 connect the two travellers together, the white of your 14/3 is the netrual you've got to get from one box to the other, and at the far end, you connect 14/2 from the switch to the light with the black of the 14/2 connected to the common on the switch, and the white connected to the white of the 14/3.
If it's a switch loop, then you send constant power to the light, run 14/2 to the 1st switch just like you would for a singe switch loop (white is constant hot, black is return switched hot). You still connect the two 3-ways together with 14/3. Two wires connect the two travelers together, and the third wire connectes to the common terminal on the far side. So back at the 1st switch, you connect the two wires from your light to the common terminal of the switch and the other to the third wire from the common at the far side of the switch. Now this part I'm not sure about, but I THINK the standard for running the 14/3 between the two switches is to either connect the white of the 14/3 to the hot white of the 14/2 from the light, then use the black and red as the travelers between the two switches... OR connect the hot white to the common of the switch, use the red and white of the 14/3 between the travelers, and the black of the 14/3 from the far side common back to the black to the light.
With any of these setups, anywhere you have a constant hot AND a neutral, you can pigtail off of that to go to the next outlet. keep in mind that even though white wires are used in switch loops, because they are being used as a hot, you can not pigtail off of wires that are in the middle of a switch loop... because a switch loop (by definision) is a constant hot wire to the switch and a switched hot comming back.
NOTE: The picture Secutanudu provided is something of a cross between simple switching and a switch loop. It's not totally a switch loop because you don't send the hot to the light 1st. But it's also not completely a simple switch as the neutral doesn't come with the switched hot. Notice how the netrual from the original power source goes only to the light bulb in the 1st half of the 14/3, but the 2nd half of the 14/3 is like a switch loop.