Steve Ince - Most of my ideas come from characters I've created and thinking about what they'd do if they were put into a certain situation.  For instance, in the Juniper Crescent comic strip, Scout has little bit of a reputation for telling tall stories about his fictitious exploits.  The Sapphire Claw is basically what happens when someone uses this against him and effectively forces him into an exciting escapade for real.

Jonathan Boakes - Memory, and experience. I have a huge back catalogue of ideas waiting to undergo the development process. Many of these ideas are infused with memories of old tv shows, and films, seen in childhood. I had a truly adventurous childhood, so there's plenty of fuel for my aging (maturing!) imagination.  

Britney Brimhall - I tend to use real life people and events as inspiration.  Books, movies, other good games, and travels also offer a plethora of ideas.

Tamás Marosi Z. (Pierrot) - I must be influenced by the fact that I continue to play (adventure) games, but they are not an immediate influence: I try to walk my own way. The makeup of the story of adventure games requires a different kind of logical thinking, which, if can acquire it enough, can serve as a filer through which we can build all kind of useful information into our current game project. I look for legends, stories, curiosities to the given scene, historical situation, culture and convert these slowly.

Mikael & Eleen Nyqvist - That's kind of hard to say exactly. From films, books, stories, and other games. Probably from everywhere.
 

Matt Clark - I find myself influenced all the time, by film, theatre, etc etc, but most rewardingly I am influenced by Cornwall, and the land around me. Inspiration comes quickly when based in an inspirational landscape.

I'm a big fan of cult British TV; accessing a friends extensive television archive provides much in the way of inspiration, and highlights how small productions have pulled off big ideas, on a shoestring budget.

I also enjoy bouncing ideas about with friends, (some of whom are developers, designers, directors, writers etc). They offer up directions to follow and other inspiring material to consume, as well as getting involved with some aspects of the production.

Cos Russo - I loved the effect that Riven had on me; I was somewhere else for the time I was playing it.  At the time, I felt it was the closest thing to being in a movie and was excited by the idea of creating my own world.

Agustin Cordes & Alejandro Graziani - Did you watch the movie Altered States where the protagonist goes on a inspiring spiritual journey to some African country and ingests a crazy drug that induces hallucinations, forcing him into a deep comma-like state from which he returns with an unparelled knowledge of life and the Universe?

Me too! Pretty weird movie... Anyway, inspiration can come anywhere from books, movies and locations that you visit. For instance, the greenhouse, crypt, and chapel in Scratches were all designed after very real locations that Alejandro researched. Its story has been influenced by H.P. Lovecraft, Lucio Fulci and 70's horror pictures, most specifically Hammer Horror films. My morbid love for basements comes from the movie that possibly changed my life forever: Fulci's House By The Cemetery. Trust me, it isn't advisable to watch that flick at the age of seven.

I should add though, that the core element of Scratches was inspired by a weird dream that I had. Can't say anything about it other than it involved (surprise!) a basement.

Chris Brendel - I come up with the ideas for my games through a combination of personal life experience and dreams.  That is not to say, of course, that I once visited a small town that hid a dangerous secret!  I did once, however, pass through a small town where I felt distinctly like an outsider, and I was a little creeped out by their overt friendliness and openness with each other and me.  I wanted to explore this feeling in Shady Brook.  When it comes to the actual plotting of my games' story, however,  I am a bit more abstract; I usually draw upon dreams that I have had, which was the case for many aspects of Lifestream.

Bryan Wiegele - I think imagination is an unpredictable beast and great ideas can come from the most unrelated subject. I've been in public places before where I've noticed people who just set off my imagination as in 'what if THAT person was in my game, what would her motivation be?' While I think everyone is influenced by movies, music and art, I think a lot of my inspiration comes from real life people and places.

Gey & Silvio Savarese - We would say from everywhere! Capri game's inspiration clearly came from some SF classics where ideas such as time traveling and parallel universe are common. But, as many players can confirm, the game's story is very light-hearted and all these themes were carried out with a lot of irony. The idea was to give some fun entertainment akin to a vacation trip to a Mediterranean island. Anacapri instead has a more 'serious' story line. The idea comes again from literature, again fantasy/SF, history (Greeks, Roman Empire and so on), Freud (Interpretation of Dreams), ancient mythology, movies (wizard of Oz), true history and legends of the Capri island… and, much, much more…

Michael Clark - I basically just use my imagination, and think up a good story, one that I'd like to see as an Adventure Game.  With both Harvest and The Arrangement, I had the over-all plot already worked out but actually fleshed it out as the game was being made.

Knut Mueller - From everything I'm interested in: reading books, watching movies, playing other games, visiting museums or walking in nature.
 

Keith Nemitz - From playing games, all kinds. From being playful, in general, too.