A free collection of soviet military maps at 1:100,000 available to download at http://www.topomaps.eu/asia/tadj_100k.shtml
The University of Texas at Austin provides its collection free for download at http://www.lib.utexas.edu/maps/tajikistan.html
Google maps service provides shaped and satellite maps at maps.google.com
Printed maps available from the following publishers:
Gecko Maps 1:500,000 : http://www.geckomaps.com
Cartographia Maps 1:750,000 available at: http://www.cartographiaonline.com
A number of on-line shops offers a wide range of maps from different publishers:
Navi Maps http://www.navimaps.co.uk/
A well detailed Soviet military maps at 1:100,000 and 1:200,000 can be purchased while travel in Central Asia republics but they usually printed in Russian and therefore requires some knowledge of Cyrillic:
1. Geoid map shop: Kyrgyzstan, Bishkek, Kievskaya str 107.
2. GEO map shop: Kazakhstan, Almaty, Satpaeva str 30B
Cover up any maps at border crossings and when dealing with officials like police or KGB, as they can retrieve them without notice. Its not basically said anywhere you cannot use the maps but its better not to mention or show them up unless very necessary.