Basically what I always did was take MS Paint (I started this habit on my Win95 machine and never really graduated beyond it), and make a basic map, and then give it numbers. Then I had a list of what each room was/who was in it/list of events that could be rolled for corresponding to it's number. I used to have some "images" of building outsides and stuff, as well as the number lists, but they are all long gone to me - however, I still had the maps laying around, so I grabbed the 16 best ones and put them in a .zip folder so anyone that is GMing can use 'em if they'd like. These were more for GM's use, as they're not flashy enough to show a player (maybe outside of building blueprints or schematics, and even then it's iffy). Made it easy for me to keep track of team progress.
If you want to view 3 screenshot samples of the maps, go here:
http://sites.google.com/site/vegetaman/home/shadowrun/mapsIf you want to download the .zip (16 maps in all across 8 "sets", it's here:
http://www.mediafire.com/?unnfmuvziztThey're not the greatest, nor the flashiest, but they got me by for many a session and many a group of SR3.