I was actualling going to suggest Flash...but you're already aware of it; and it's not the first thing that comes to mind when thinking of drafting applications.
Unfortunately, I can't think of any others; and thinking about how such programs function, such a feature would be mostly hugely counter-productive. I don't imagine any CAD programs would oblige; and sticking with the more artistic packages, Illustrator and CorelDraw certainly won't do it either. I'm not sure of some of the 'B list' like Serif Draw.

Ten steps to get your data points of a true spline curve

Download Bezierspline
by Fredo6
Complete set of polylines and splines curves commands: create, modify, convert. Cubic Bezier spline curve2, Uniform B-Spline, Polylines, modification of precision, add/delete control points, support of loop closing, conversion of any curve to spline curves, language translation support (French, German, English, Hungarian, Portugese). Doc included.

Download Silhouette to Plan.
by TIG
Flattens (projects) the selected geometry onto the selected workplane. edges are inspected and only those that are needed to form a fully faced 'silhouette' WITHOUT cut-outs are retained.

Use tip 1 runing more than one sketchup.
http://forums.sketchucation.com/viewtopic.php?f=79&t=40254

Run 2 copy of sketchup - two click of the shortcut.

Make your shapes or objects with Bezierspline and Silhouette (per #1 sketchup).

Select curve (per #1 sketchup).

Paste in place to empty page GUI (per #2 sketchup).

Sketchup
a) Export file.dae (per #2 sketchup).
b) Meshlab.exe convert dae to wrl.
or

SketchupPro
Export file.wrl (per #2 sketchup).

Open file.wrl - Notepad.

Read your data points.

Microsoft Visio (costs,) or the free open-source clone OpenDraw (part of OpenOffice.)
http://www.openoffice.org/

You may wish to try out DoubleCAD XT it's a free AutoCAD LT clone from IMSI.
http://www.doublecad.com/

Adding my kind upvote for this!!!