Thanks to Jim Gray for passing these links on. If you are building your own home, you can apply for a rebate on the GST.
Fill in the worksheet, then federal, then provincial forms.
The worksheet: http://www.cra-arc.gc.ca/E/pbg/gf/gst191-ws/README.html
The federal form: http://www.cra-arc.gc.ca/E/pbg/gf/gst191/README.html
The provincial form: http://www.cra-arc.gc.ca/E/pbg/tf/rc7191-bc/README.html