how to extrude a cross-section along a path

It was easy in pre 2.6 using the dupli-frame feature, now I can’t figure it out! No luck with the tutorials or searches.

you could use the bevel object ( bev ob ) feature

That just cuts corners on the extrude feature, neither of which is controlled by any outline. Extruding an outline along a 3D path was a mainstay of old Blender, and still the easiest way I can think of to make ropes, tentacles, chain-links, plant stems, and other path-like objects. (the plugins make a few of these easy but I need a general solution for basic modeling competence ! )

Use curves… with a bevel object and taper object if desired. You can always convert to a mesh when done.

ok, that works.
For those who need a little more detail: (a rope example)
-add one of the items from the Add Curve menu to define the path of the robe. Go into edit mode and move the points around to shape the path you want.
-add another curve object from the menu to define the cross-section of the rope. Edit that to make your cross-section shape as you want.
-select just the curve defining the path
-In the Properties window, under the Object Data tab, find the section labeled Geometry, and in the Bevel Object: dropdown select the path curve you made. It will instantly inflate to a 3D shape. You can edit either curve in real-time to finalize your object.
-When satisfied, you can keep it as it is, but only a limited set of tools are compatible with curve-based objects.
-if you need to use mesh tools on it, go to the 3D window menu, select Object->Convert to -> Mesh. The resolution of the mesh is based on the resolution in the curve settings. Because converting your mesh back to a curve for easy editing is not very reliable, you should save a copy of your curve object before converting it to a mesh.

-Taper Object: you can use another curve to define the SIZE of the outline as it progresses from one do your path to the other. It’s not obvious exactly what property of the Taper curve is used, you will have to experiment. Anybody want to elaborate on that?

Hope this helps somebody.