This is genius. Genius I tell you.
If you want to be able to use any coffee in your Kuerig brewer check out this Solofill Cup, Refillable K-Cup For Keurig Brewers. It has 31 reviews and 29 of them are 5 star, so this must be a good product!
There is the cost or purchasing up front, but the amount of money you can save on coffee (not to mention the impact on the environment) should make this a worthwhile investment in the long run.