Periodically, posters inquire specifically about finding a restaurant that is open on Mondays. I think a thread dedicated to a list of Monday-friendly suggestions could be as useful as the "Closed on..." thread. A quick Google/LTH search netted me this list, which I have not confirmed, but serves as a good place to start:
Riccardo Trattoria
A Tavola
Sola
Mercat a la Planxa
Bin 36
Custom House
David Burke's
Kiki's Bistro
Mon Ami Gabi
Nomi
Roy's
Sweets & Savories
Big Jones
Bistro Campagne
Sepia
Crofton on Wells
Publican
Gaetano's
Cemitas Puebla
Semiramis
Lao Sze Chuan
Katy's Dumplings
Quartino
I'm certain there are many more...