The following list is a list I have compiled of Free Canadian GIS data. Before you rush out and buy expensive data, why not see if they have it here for free? The list has a lot of national data, but I apologize if it is a bit Ontario Centric. Since Ontario is where I do the majority of my work....
http://www.geobase.ca - Fairly updated, provides SPOT radarsat data for all of Canada. This is incomplete - should be completed by 2010. Also provides an up to date national road network, a hydro network for Canada. Landsat 7 10-30 m cell size satellite imagery for all of Canada.
http://www.geographynetwork.ca/ is a site published by ESRI Canada that provides free obm data for all of Ontario. You can find the free Ontario OBM data at : http://www.geographynetwork.ca/website/obm/viewer.htm specifically. All you need to do is sign up to get layers like forest, drainage, contours, roads and more. I should not that the data is often outdated and temporally sensitive features, like roads, may be quite out of date (circa 1998)
http://geogratis.cgdi.gc.ca/geogratis/en/index.html provides a whole gamut of Canadian geospatial data. There is simply too much to indicate here, you need to check it out for yourself. Some of the things I have used in the past are vegetation indices, population maps and more!
http://geodepot.statcan.ca/Diss2006/DataProducts/RNF2006_e.jsp - Statscan only provides road networks for free and I have yet to explore the data. However, I have heard they are fairly up-to-date and provide street names in the attributes. The data apparently is as recent as 2007, which beats the geographynetwork hands down
More is coming soon on this topic.
