SVG is now supported by all web browsers, a number of applications, Inkscape is free. Use it as an output format when it's available!
(As to "converting" a scanned drawing to SVG, there are apps for that too. But I don't know of a good, open-source one. Is there any?)
Do you consider Inkscape's own
Path >
Trace Bitmap "good"?
To test, one can import an image, then select that image, and
Path >
Trace Bitmap. The
Live Preview uses a blocky version of the results, and is fast, and thus can be useful in fine-tuning the parameters; but the
Live Preview is not nearly as high fidelity as the results are.
I don't know how useful that is in practice for scanned line drawings, because like I said, I re-draw the diagrams etc. from scratch, typically in Inkscape or Dia. Sometimes (isometric 3D views etc) I use a script or a program to generate the SVG. And I like to fine-tune them by hand, omitting the SVG width and height attributes, leaving only the viewBox attribute, so that the SVG will fill whatever region it is displayed in.