There's been a bunch, but I'm only now posting them, because I haven't posted anything in a month and more. God, that's terrible.
Fleming's Steakhouse closed some months ago, although I only heard about it last month. Harbor Place, where the most remarkable thing about the place was that it had an airplane bathroom, is also gone. Functional Fuel looks totally dead. The Belltown Pub is gone, but I didn't care for it much, so oh well. Figaro Bistro, an overpriced place apparently much beloved by Seattle's French community, closed a couple weeks ago.
There's probably more, but that's all I know about right now.