This is the solution chosen for a web interface as simple as possible to make it compatible with mouse or touch screen.
No various gesture or mouse drag, simply click on the spot where you want the new centre of the map.
Click on + to see more details and on – for less.
Click on the drop down list to choose by a click the offset applied to zoom.
Could it be simpler?
Follow @lbarme on twitter to get an access code to try it by yourself…