You can do any brown sauce as a reduction .. you just need to use a good gelatinous stock.
I have used balsamic as well but I take the vinegar reduction and add it to an espagnole (reduced veal stock).
One I have used latley is a Hunter style ..
Saute shallot and onion, add mushrooms (any type or mix), add garlic, deglaze with red wine, add espagnole and reduce to nape, add tomato conccasse, season to taste.
Also a good seller (in Texas anyway) is 'Diablo' -- saute shallots, add garlic, deglaze with red wine, add espagnole and reduce to nape, season with black, white, and cayenne pepper to taste.( I use a 'cajun ratio':1 bp to 1/2 wp to 1/4 cayenne)
Both of those sauces are based off of classic French but use reduction in place of a roux.
We did nothing but reductions in the early eighties .. nouvelle cuisine at it's best, and most expensive
[This message has been edited by Wambly (edited August 19, 2000).]