Optimize Your Laser Files
These 2 commerical software packages will help you optimize your files by stacking objects as close as possible to each other, and eliminating duplicate lines:
Only does nesting, not duplicate line erasing. Works as a plug in for Windows Illustrator CS5 and later. Unfortunately doesn't work with CS2 or Macs.
Powerful, with nesting and merging of common lines so the laser doesn't cut the same path twice. Stand-alone software. Expensive, costs up to $7.50 per file processed.
Free open source, made by the same author as Deepnest. Does not do line merging.