Inkscape 0.47 and later will support curve editing via Raph Levien’s vastly superior Spiro curves:
I round-tripped through FontForge when I drew the Seal of Rassilon for a recent t-shirt design, just so I could use spiros to do it:
Achieving nearly perfectly tangent and parallel curves using spiros is trivial, compared the the fragile finickiness of Béziers.
Spiro 0.01 is finally out! Spend ten minutes learning how to edit Raph Levien‘s Cornu spiral curves and you’ll see that they have the potential to complement or even displace Bézier curves in vector and font design programs.
Spiro will be the native algorithm for Fontly.