While I was working on manipulating quite a few nodes trying to align
them to a path, I thought it would be useful if there was a function
which did this in Inkscape.
You would need to select a path and a node, and the selected node
would automatically be moved to the path. The node would travel the
path like it was a rail, with only 1 dimensional movement. Many
otherwise difficult tasks then become easy. For example, if I were
trying to make a pizza I would:
1. Draw a circle
2. Draw a triangle within the circle with the base facing the outside of
the circle (like a pizza slice)
3. Select the one of the vertex bases, alt shift click (or maybe a lock
node to path button in the node editing interface) the circle and then
move the node to lock on the base
4. Select the other vertex and perform the same operation
5. Select the base of the triangle and make it smooth
6. Do a clone + rotate operation
Now I you would have a decent looking pizza with slices and all. Of
course the primary reason for having this feature would not be to
make pizzas but rather shapes that are related to the shape of
another in only a few vertices (the offset feature would still be useful
as it is more geared towards shapes that inherit the flow of many
vertices). You could also use this feature like a much more flexible
guide: you could make a quick curve to lock to, or even just an
angled line.
In addition to this, when multiple nodes are selected they follow the
path like a train, keeping the same distance apart that they originally
had (sqrt(dx^2 + dy^2)).
I agree that something like that will be useful, but please
realize that in general case, it is impossible to move a
node along the path without distorting the path. We can
however attempt to minimize these distortions.
As for pizza slices, you can easily do them currently with
our Ellipse tool which can do arbitrary sectors and segments
(see the Shapes tutorial).