You can setup speedometer to use any kind of your own map tiles url source. Pattern should contain {x}, {y}, {z} variables for x coordinate, y coordinate and z as zoom. Supported projection is a spherical one (same as Google and OpenStreetMaps are using by default).
Some map providers like Yandex for example is using elleptical projection and thus their tiles are not supported at the moment. Some providers, like Bing from Microsoft is using a quad schema with {q} parameter - this is not also supported in the current version. Support for Bing and Yandex type of map providers will be provided in the future versions.
Here is just some inspiration for map sources that can be used under terms and conditions of their providers.
Please be sure to consult each map provider terms of usage and license information before actually using their data!
We don't have all of those urls tested, please see for yourself what works and what does not.
Esri Navigation Charts (parts of the world, zoom 0..10)
http://server.arcgisonline.com/ArcGIS/rest/services/Specialty/World_Navigation_Charts/MapServer/tile/{z}/{y}/{x}.png
Esri World Imagery (zoom 0..17)
http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}.png
Esri National Geographic (zoom 0..12)
http://server.arcgisonline.com/ArcGIS/rest/services/NatGeo_World_Map/MapServer/tile/{z}/{y}/{x}.png
Esri Physical (zoom 0..8)
http://server.arcgisonline.com/ArcGIS/rest/services/World_Physical_Map/MapServer/tile/{z}/{y}/{x}.png
Esri Ocean (zoom 0..10)
http://server.arcgisonline.com/ArcGIS/rest/services/Ocean_BaseMap/MapServer/tile/{z}/{y}/{x}.png
Esri Reference/World Transportation (zoom 0..18)
http://server.arcgisonline.com/ArcGIS/rest/services/Reference/World_Transportation/MapServer/tile/{z}/{y}/{x}.png
Esri World Topo Map (zoom 0..18)
http://server.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer/tile/{z}/{y}/{x}.png
Esri World Street Map (zoom 0..18)
http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}.png
Google Hybrid
http://khm1.googleapis.com/kh?v=142&x={x}&y={y}&z={z}
http://mt1.googleapis.com/vt?lyrs=h&x={x}&y={y}&z={z}"
Google Satellite
https://khm1.googleapis.com/kh?v=142&x={x}&y={y}&z={z}
Sample to verify: https://khm1.googleapis.com/kh?v=142&x=31948&y=20974&z=16
Google roadmap
http://mt1.googleapis.com/vt?x={x}&y={y}&z={z}
Google road & terrain layers, with high-res (Retina) support
roadmap
http://mt1.googleapis.com/vt?x={x}&y={y}&z={z}
terrain
http://mt{s}.googleapis.com/vt?lyrs=t,r&x={x}&y={y}&z={z}
OSM Thunderforest Cycle (zoom 0..18)
http://1.tile.opencyclemap.org/cycle/{z}/{x}/{y}.png
OpenCycleMap with train & tram lines
http://1.tile2.opencyclemap.org/transport/{z}/{x}/{y}.png
http://openstreetmap.org/copyright
Piste
http://tiles.openpistemap.org/nocontours/{z}/{x}/{y}.png
Relief shading
http://tiles.openpistemap.org/landshaded/{z}/{x}/{y}.png
Sea marks
http://tiles.openseamap.org/seamark/{z}/{x}/{y}.png
If you find an error in one of the urls or have a new url to share, please feel to drop us a line via the feedback window!