I've been a pretty active member of the Yahoo group PFMSIG over the years, but haven't participated in that one or many other discussion groups very much lately. I can also attest it's a great group with many people willing to share ideas and help you work through any problems you run into.
A few months ago I created a composite system map of the members of the Yahoo group who offered their maps for me to include. I received a number of additional maps after putting forth the first effort, but due to time constraints (all my computing time at home is spent on 3D animations lately) I haven't updated the maps. Here's the site if you're interested in seeing the maps:
http://www.geocities.com/pfmsigmaps/master.html
It's a huge map, so dial-up may be slow loading it. Clicking on any of the individual tiles will open the detailed map for that area. I still need to add the roadnames to each color coded line, but in general, gray colors are for the prototype roads where a PFM road has trackage rights.
Naturally, I have my own PFM line, the Pine Valley, and the website for it is located here:
http://www.geocities.com/norfolksouther ... /pvrr.html
I've also written a piece on developing my railroad's paint scheme for Hub Hobby Shop's website located here:
http://www.hubhobbyshop.com/empire5.htm
For topographic maps, terraserver is good, but I like topozone.com even better
http://www.topozone.com/viewmaps.asp. I've used that site to create a full "strip topo" of my railroad's route from Gallup, NM to Vallecito, CO which was used to position the alignment of the railroad with a ruling 2% grade. It doesn't hurt that I work in the civil engineering industry, so I have access to all kinds of good software to do this! You might also want to check out the government website for the municipality you're interested in modeling. Tax maps can be a great source of information for locating existing railroads and in some cases, you'll find aerial photos and other mapping for your area. In my area, the best resource for this kind of mapping is
http://www.dfwmaps.com/, so if you can find a similar site for the area you're modeling, you'll have plenty of information at your disposal.
It looks like you'll have answers to any questions you have without even having to leave this site, and that's a credit to the efforts of Otto et al in establishing and maintaining this site over the years. You're hard pressed to find a better group of folks than the ones here.