There's no special secret to cross bracing. No special material, no special technique. You may remember the old cross bracing between our joists -- it was made of spare pieces of hardwood flooring. For the new cross bracing, Don and his dad just used spare pieces of joist beams, since they had it around from putting in new joists (this technically makes it "solid blocking", since it's just one piece of wood). They measured carefully and cut a piece of the board exactly to fit in between each joist (yes, you have to measure each space, since they are all going to be a little different) and then just nailed it into place.
The one thing they did differently than the old system was to actually add more cross bracing. Originally, the bracing just went in a straight line across the middle of the room. What we did instead was to install cross bracing at every seam in the subfloor. Every place where one sheet of plywood ends and another starts is reinforced with cross bracing all the way across. Basically, this winds up meaning that there's a row of cross bracing going across the entire space every four feet (since plywood comes in four-foot-wide sheets!). It makes the floor a lot more sturdy.
Good construction starts where you'll never even see it. Doing it right the first time means we won't have to go back in and do it again, and what we're building will last a long, long time. Adding the cross bracing every four feet certainly adds some time to the process, but it also creates a really strong foundation for everything we're going to build on top of that subfloor.
And heaven knows we don't want our grandchildren going in and renovating this house many years from now and complaining about us like we complain about this stuff!