WareLogging, GerberFiles.

* http://www.batchpcb.com/
* http://www.freepcb.com/

* [http://www.apcircuits.com/resources/information/nc_codes.html NC drill file codes]
* The closest thing I've found to a useful [http://www.artwork.com/gerber/274x/rs274xrevd_e.pdf Gerber spec document]
* [http://www.pcbstandards.com/forums/ pcbstandards forums]
* [http://gerbv.sourceforge.net/ gerbv]
* [http://www.lis.inpg.fr/realise_au_lis/kicad/ Kicad]
* [http://geda.seul.org/ gEDA]