ArcBruTile display tiles from OpenStreetMap, Bing, Google, SpatialCloud and TMS/WMS-C Services in ArcGIS Desktop.

GMap.NET is great and Powerful, Free, cross platform, open source .NET control. Enable use routing, geocoding and maps from Google, Yahoo!, Bing, OpenStreetMap, ArcGIS, Pergo, SigPac, Yandex, Mapy.cz in Windows Forms & Presentation, supports caching and runs on windows mobile!

Serverside geocoding wrapper for various geocoding services. Supports a failover in the event you get throttled.