I am not sure if this is a weird thing to post, or a weird place to post it, but I know he had a lot of friends in the mu* community, and I am sure some people still remember him fondly.
I'm very sorry to say that EUBanana/Anarchy/Death of The Greatest Generation fame passed away last week. It was not entirely unexpected, but he was still working on this living thing despite being very ill, and though things had gotten quite rough. That his pain is over can be the only solace for those who loved him.
I am sorry to share such news but, in the ether, we all come and go so mysteriously. So I felt the need to share, so those who wish to mourn him, can. Because guys such as he deserve to be missed, and their friends deserve to know when they've left this world for some other adventure.
No wise words to end on, besides: when you love and value people, tell them so.
Cheers to a really good guy!

The setting of the Dishonored games.
Alternatively, but less detailed, the setting of Thief, the Dark Project.

But seriously, Dishonored has an amazing setting. The Outsider, the dystopian steampunk vibe. Wicked nobles, betrayals, a guild of thieves, creepy religious tones. So many ideas for characters, so much style, so much atmosphere.

And another idea would be Gene Wolfe's Urth of the New Sun setting. Far flung future, guilds (including, of course, the Torturer's Guild!) wild imaginative dark delight. A decaying world so far into the future it's difficult to comprehend-- well, might not lend itself as well to a structured game, but something inspired by it would be amazing.

What's SSL? >_>