Dan John had an interesting article, in which he hypothesizes that loaded carries are one of the single best things an athlete can do for their performance. I'd played with suitcase carries a bit a while back,but feel off it because I wasn't integrating them into my training well (read: I was tired and everything hurt all the time). Dan's article inspired me to give it another shot. Me being me, I was super short on time, so I tried a slightly different workout then the one he outlines (though I want to try his as well).
(With a 36 pound kettlestack):
Suitcase carry bell to end of driveway (or do three laps in my basement, depending).
Switch arms. Repeat.
The first time I tried this, I figured I'd shoot for ten minutes, since I was, after all, using the lighter weight. After five minutes, my heart-rate was through the roof, and my hands didn't work. So ten is now a long-term goal, not an immediate one.
I plan to keep experimenting with it, but it's a damn good workout, especially in a time crunch.