I'm quite the fan of a stack of 6" lengths of 2' x 4', placed right under the oil pan. Very secure! Such stable! :hehehe
Or how about this one!
But in all seriousness, Al's design looks like a good concept. For front end stuff, I've been using one of those red hydraulic two-pronged "motorcycle jacks". They're generally pretty terrible, but with the bike still supported by the centre stand in the rear, it's fine for front end work (e.g., removing front wheel, steering head bearings, etc) For rear end stuff and spline lube, well that's another story. I've done the sawhorse method, and on another occasion, the "box" support.
An improved design for this is definitely warranted.