SHOTGUN ADAPTERS!!!
Firearm versatility at its finest! These folks should be making loads of $ with this great idea!
http://www.youtube.com/watch?v=CRZXyFsWsG8
Take your single-shot shotgun and load up with .22, .410, 38, or 20ga rounds!
http://shotgunadapter.com/
Those of you that have significant metalworking skills may be interested in making your own, please comment and let me know how it goes!