It was confirmed by his producer that his last album was indeed a goodbye of sorts. No one knew he had cancer except for his immediate family and his close business partners (such as his producer).
Since he passed, a lot of obscure things have been popping up about him. I'll detail 2 of them.
First, he was in a video game called Omikron: The Nomad Soul which released on The Dreamcast and PC in 1999. Bowie, who had some input on the storyline and game's design, makes two cameo appearances within the game, although not as himself; first as Boz, a game character who's a revolutionary wanted by authorities, and secondly as the nameless lead-singer of the fictional musical group, "The Dreamers", who perform illegal concerts in Omikron.
Video:
You can find the game on Steam if you are interested, for $9.99.
http://steamcommunity.com/app/243000
Second, back in 2004, author Neil Gaiman and Yoshiitaka Amano (the legendary Final Fantasy illustrator) collaborated on a story called
The Thin White Duke, a sci-fi reimagining of one of David Bowie's personas of the same name. In a recent interview with the Chicago Tribune, Gaiman explains the the story was written in two parts, with the first part featuring Amano's illustrations.
"It was written in two parts. I finished it for this book, but the first part was with artist Yoshiitaka Amano, who was commissioned to do pictures for a magazine called V. His images were Bowie and (Bowie?s wife, the model) Iman as sci-fi characters. Then I was asked to write a story, so it became about Bowie and Iman in this future New York." ? Neil Gaiman
Artwork in the spoiler below.