Brown butter?

Question from a friend: What's "brown butter sauce" all about? (Too
lazy to go into the next room and consult the Joy of Cooking).

Brown butter is also called beurre noisette or buerre noir, depending
on how distracted I get from the cooking process. It's basically
browned or burned butter, respectively, sometimes with a dash of lemon
juice to emulsify it. I was just thinking it's a good way to give some
extra flavor to the crabmeat. In effect, you're adding clarified
butter, which we all know has a big affinity for lobster and crab,
plus some nutty flavor, which should complement the roux in the
bisque. Just put a couple tablespoons of butter in a heavy skillet and
heat over medium-low heat until the foam has disappeared and the
solids start to take on a brown color, then throw in the crabmeat or
shrimp and squeeze a teaspoon or so of lemon juice over the top. Stir
vigorously until the crab is heated through or the shrimp is mostly
cooked, then put on the bisque.

The Joy of Cooking will make you think this is the wrong way to do it.
The cooking-industrial establishment will tell you that this is a very
slapdash way to make a beurre noisette. The cooking-industrial
establishment should get a full-time job. They should also stop
trying to sell us things we don't need. Ladies and gentlemen, the $20
replacement for the beer can: the vertical chicken beer roaster. Do not buy this product.