What Modest Maps does:

• Displays tile-based maps, from sources such as
  OpenStreetMap,
  NASA Blue Marble,
  Google,
  Yahoo!,
  Microsoft,
  and others.
• Supports developer-defined tile sets in arbitrary
  geographical projections.
• Smoothly pans and zooms.
• Tracks the position of geographical map markers.
• ActionScript 2.0 codebase works with FlashLite.

source : http://modestmaps.com/