I also add worcestershire and bay and thyme and a tiny bit of anchovy paste, not enough to notice but for that umami.  Jim's burger trick sounds great. Something bright as a garnish/finish is good, like Jim's use of vinegar or the horseradish.  A little tomato sauce in the stock can also be really good.  When Anna Selma made it at Tony's she used tomato sauce and white wine and it was awesome. As Mark pointed out, there are many variations.