You can download these free maps of Sri Lanka in pdf format. Some of these maps are interactive maps and Google maps.
Road Map of Sri Lanka by Survey Department
http://www.lakdasun.org/forum/doc_base/Road_Map_New_Edition-Final.pdf
National Topographic Maps by Sri Lanka Survey Department
http://www.survey.gov.lk/surveyweb/Home%20English/Map%20Index.php
Tourist Map of Sri Lanka by Sri Lanka Tourism Promotion Bureau.
A comprehensive map of Sri Lanka’s road systems, historical and religious sites, forests and Wildlife sanctuaries, harbors and diving sites, a guide to explore the country, find your way around or guide to simply to get lost amidst the splendor and beauty of the country.
http://www.srilanka.travel/interactivemap/
Beach Tourist Destinations by Trip2Lanka.com
World Heritage Sites Map by trip2lanka.com
Sri Lanka by Rail by Sri Lanka Railways
http://www.railway.gov.lk/web/images/pdf/railway_toursim_sri_lanka.pdf
Sri Lanka Reference Map
http://reliefweb.int/sites/reliefweb.int/files/resources/8149F7590823501EC125779800335DEB-map.pdf
Province, District and DS Division Boundaries of Sri Lanka Map
by Department of Census and Statistics
http://www.statistics.gov.lk/misc/Map%20of%20Administrative%20District.pdf
Sri Lanka Distance Chart
http://www.akdmc.com/srilanka/downloads/upload/Sri-Lanka-Distance-Chart.pdf
Map of Sri Lanka by Lonely Planet
http://www.lonelyplanet.com/maps/asia/sri-lanka/
Travel Guide Maps by Orangesmile.com
http://www.orangesmile.com/travelguide/sri-lanka/country-maps.htm
Detailed Road Map of Sri Lanka by Maphill
Detailed Road Map of Sri Lanka
Routemaster: Sri Lanka bus maps and route planning
Sri Lanka @ d-maps.com
Sri Lanka: free maps, free outline maps, free blank maps, free base maps, high resolution GIF, PDF, CDR, AI, SVG, WMF.
http://www.d-maps.com/pays.php?num_pay=108&lang=en