Leaflet.MiniMap is a simple minimap control that you can drop into your leaflet map, and it will create a small map in the corner which shows the same as the main map with a set zoom offset. (By default it is -5.)
The control can be inserted in two lines: First you have to construct a layer for it to use, and then you create and attach the minimap control. (Don't reuse the layer you added to the main map, strange behaviour will ensue...)
From the example:
var osm2 = new L.TileLayer(osmUrl, {minZoom: 0, maxZoom: 13, attribution: osmAttrib});
var miniMap = new L.Control.MiniMap(osm2).addTo(map);
As the minimap control inherits from leaflet's control, positioning is handled automatically by leaflet. However, you can still style the minimap and set its size by modifying the css file.
Note: Leaflet version 0.5 or higher is required.
The mini map uses options which can be set in the same way as other leaflet options, and these are the available options:
position: The standard Leaflet.Control position parameter, used like all the other controls. Defaults to 'bottomright'.
width: The width of the minimap in pixels. Defaults to 150.
height: The height of the minimap in pixels. Defaults to 150.
zoomLevelOffset: The offset applied to the zoom in the minimap compared to the zoom of the main map. Can be positive or negative, defaults to -5.
zoomLevelFixed: Overrides the offset to apply a fixed zoom level to the minimap regardless of the main map zoom. Set it to any valid zoom level, if unset zoomLevelOffset is used instead.
zoomAnimation: Sets whether the minimap should have an animated zoom. (Will cause it to lag a bit after the movement of the main map.) Defaults to false.
toggleDisplay: Sets whether the minimap should have a button to minimise it. Defaults to false.