Stumbled across ArcBruTile, an ArcMap application that allows you to display map tile services–such as OpenStreetMap, Google Maps, Bing, Spatial Cloud, and Tile Map Service (TMS)–in your ArcMap documents. It works pretty well from my preliminary testing of it. I have found that at times that the graphical tiles are distorted but I am guessing it is because they are optimized for display in a specific projection, at specific scales and, in ArcMap, you can use any projection/scale combination you want.
This is a free, open-source project that is still in Beta but definitely an application I plan to keep an eye on. As with any open-source project, the cool thing is the code is available for you to look at, learn from, and hopefully contribute to.