I do all my laser cutter designs in inkscape and then laser cutting and etching from adobe reader resulting a totally no cost software process flow. We have done over several thousand designs this way in the Fab Lab at the Museum of Science and Industry. Here is the process to get inkscape to work followed by a simple explanation of why I believe this process flow works and is good:
1. Design in inkscape
2. Using Object, Fill and Stroke set the following
3. Fill Tab: No paint (x) unless you want to etch the whole object solid
4. Stroke Paint Tab: Flat Color
5. Stroke Style Tab: width .001 in for cutting .015 or larger for etching
6. Make sure blur is set at 0% and opacity is set at 100%
7. Setting RGB values to other than 0,0,0,255 will either prevent cutting or lighten and or change the level of etching.
8. Save a COPY of you work as a PDF, DO NOT use the normal save as function, it may mess up your original native inkscape svg file possibly making it un-editable.
9. Open your PDF file with adobe reader send it to the laser cutter, go about setting up your powers and speed etc like normal.
That's pretty much it.
This process uses open source inkscape and free adobe reader or an alternative pdf reader, so we love it at the fab lab since it allows people to design at no software cost. To spread digital fabrication to the all it's important to make sure software costs are zero.
Inkscape will work directly with the laser cutter, but it will etch (raster) everything and cut nothing. I think this is because for some goofy reason the print function of inkscape rasterizes all vectors. This makes sense because for most inkscape users a normal printer is the output device. Saving a copy as a PDF allows the vector data to be transferred out of inkscape, which upon opening with a pdf reader can be passed on to the laser cutter.