I want to display a marker on map where user taps on map.
Also this should not infect double tap for zooming and/or moving Mapview
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I
Look at OSMBonusPack MapEventsOverlay/MapEventsReceiver:
http://code.google.com/p/osmbonuspack/source/browse/trunk/OSMBonusPack/src/org/osmdroid/bonuspack/overlays/MapEventsOverlay.java
You create a MapEventsOverlay, you add it to the maps overlay, and you pass it a MapEventsReceiver in which you implement your own singleTapUpHelper code.