What to do when you don't have a panohead
If you don't have a panohead, or don't want to bring a tripod, you can still make a fairly good set of images for a panorama if you're using a wide angle lens.
If all the features are far away (over 15 feet or so) you can shoot handheld. Even if you turn in a circle around your feet, parallax won't be too bad. Or you can use your regular tripod, there'll be some parallax, but it won't be too bad.
To get a more accurate handheld panorama, use a string with a weight and a hotshoe level.
Method 1: Tie the string at about the NPP of your lens, in many cases, this will be about where the gold or red or white ring is. Tie a weight on the end of the string. The deluxe version of this uses an elastic band from a lens cap keeper.
If you can, mark the ground with a line. Then add lines to form a cross, or a star (the kind where all lines intersect at the center), one line for each two pictures you will shoot. Mark one of the lines as a starting point. Sometimes there are existing features on the ground, like wood planks that give you one line parallell to the plank, and the end of the plank gives you a line at a right angle. If you can't mark the ground, drop a coin for a center point and place another coin near it as a reference for where the panorama started.
1. Turn your body in the direction of the shot. Move your feet so that your body is straight, don't twist at the waist.If you made lines, aim the lens along one of the lines. Otherwise, look through the viewfinder to get the next picture in sequence (use about a 50% coverage).
2.Let the weight hang freely and move the camera so the weight is centered over the intersection of the lines, or your marker (whichever you used) while you remain facing in the same direction. Make sure the weight just touches the ground. Note that wind will affect the string.
3. Looking at the hotshoe level,level the camera and take the picture.
Repeat until done.
There's a good tutorial at http://one.revver.com/watch/52905 I'd add a weight on the line, reference marks on the ground, and for a spherica pano, take a full column (up and down) before you change position in the row (side to side).
This method can be modified for full spherical panos, most notably its easier to change the pitch for each shot, then change the yaw. I.e. shoot rows before columns; stand still (as above) take all your shots from top to bottom then move your feet and take the next vertical column.
Method 2:
An alternate procedure is to hold the camera over the ball of one foot, shoot a vertical row (or one shot if you're doing one row panos) and rotate about the ball of your foot. Keep the camera at the same height (its probably easier to hold it chest high than at head height) and try to keep it level (again, a hotshoe bubble level helps).
Method 3: Another method is to use a monopod and hold the NPP of the lens (or the gold, red or whatever color ring on the lens) over the center of the monopod and rotate around it. There are bubble levels available for monopods. If you're outdoors and have nothing close, just screw the camera onto the monopod. the slight parallax error won't matter if there are no near objects.