Google maps - Czech republic
Google maps is the good web site to find a place in Czech republic, you can find city and streets in the city, but Google maps does not have a database with exact street number. You can find street (Vinohradska, Prague) but you cannot specify street number (Vinohradska 12, Prague).
Seznam Mapy.cz - Czech map server
www.mapy.cz is the most known Czech map server. The web site does not have English interface, you must write Czech names (Praha instead of Prague). Site Mapy.cz has better databases than Google maps - You can find exact location of any address in Czech republic and a satellite map of Czech has better resolution than the photos on Google.