I used howstuffworks.com as starting point to better understand how tunnel making and other things worrk, as well as to find further resources. This led me to to an interesting site of a proposal to creat a tunnel from London to New York City which would take approximately 54 minutes to travel through by way of Mag-lev train. It also led me to read about a tunnel being dug throught the alps where they are making use of the mined out rock to create concrete. I also read an article about proposed (or current?) subway lines being put in 140ft. below New York City. I also looked up information on granite and other natural materials, and found that silica is present in most of the builiding materials that I would be consideriing using in my proposals, including concrete, clay, microchips, and some plants.
http://science.howstuffworks.com/tunnel.htm
http://dsc.discovery.com/convergence/engineering/transatlantictunnel/interactive/interactive.html
http://en.wikipedia.org/wiki/Silica
http://en.wikipedia.org/wiki/Silicon
To All: Feel free to edit this page and add whatever sites/tools you feel fit in to the scope of this page. Add new topic headings as necessary, the only restriction I'll put on these links is that they must be free. Enjoy.
Conceptual
size comparison tool http://www.sizeasy.com/
table of visualization methods http://www.visual-literacy.org/periodic_table/periodic_table.html
Visual Thesaurus/Dictionary http://www.visuwords.com/ (free) http://www.visualthesaurus.com/ (can try for free - nicer interface than the other)
Engineering
GlobalSpec? components (link is to mechanical components, but more are available) http://mechanical-components.globalspec.com/ProductFinder/Mechanical_Components
Material properties http://www.matweb.com/index.asp?ckck=1
many different resources available
Online conversion tools http://www.onlineconversion.com/
Reference collection http://www.martindalecenter.com/
Group / planning / management
Advanced online conferencing https://www.yugma.com/index.php
Draw and share diagrams on the web http://www.gliffy.com/
Collaborative To-Do lists http://hiveminder.com/splash/
Simultaneous drawing online http://www.imaginationcubed.com/LaunchPage
Free Software
Free Gantt chart program http://ganttproject.biz/index.php
Free image editing program http://www.gimp.org/screenshots/
Fairly powerful image processing tool
Free Microsoft Office type programs http://www.openoffice.org/
Web
Web 2.0 design guide http://www.webdesignfromscratch.com/web-2.0-design-style-guide.cfm
Free HTML Editor
http://www.evrsoft.com/1stpage3.shtml
Late Add-on: Another possibility is spider-like bots that would mine, weave tunnels, and replicate themselves at the same time. They would be mostly silicon based because of the prevalence of the material in nature. Haveing the numerous small bots instead of bigger ones would allow you to make more customized shapes and sizes of space, as well as allowing the bots to perform maintainance tasks after the habitat spaces have been dug out.