Personally, I write for me. Although, unlike what the others have mentioned, I don't necessarily stick to writing things that I fantasize about.
I like to project myself into the mind of the characters. Once I'm "in" the story, I don't think about me anymore because the story isn't about me. It's about the characters. What would they do? How would they act? What would they like or dislike? What would turn them on? How far would they go? etc....
I'm basically letting them tell me what to write. It sounds weird, but that's just the way I do it.
I don't worry so much about ratings. Some fairly random number doesn't tell me much. If others enjoy the stories I'm writing, that's great. I'm happy I could entertain someone for a little while, but I'm far more interested in their feedback than what number they gave it. Sometimes, I learn that things didn't "work" as much as I thought they did. Sometimes they give me ideas or directions that I hadn't thought of or considered. In either case, I learn something and that's fun too.
As for writer's block....good luck with that. I've had cases of it off and on myself and it's frustrating. There's really no "cure" for it that I've found. Just have to sort of suffer through it until inspiration strikes. For me, inspiration comes from a variety of things. Sometimes it's something I read online, a news paper, a book, a magazine, whatever. Sometimes it comes from something i saw on TV that sparked an idea. Sometimes I just sit and let my mind wander. Sometimes it comes from things other people have said or suggested. Usually, it's a combination of those things.
Bermuda started from a combination of something I saw on the History Channel and Lost. Once I had the basic idea, I 'created' a character, tossed him into this strange place, and then let him tell me what happened. When he stops telling me how the story goes, I throw something else at him and see what happens. Sometimes, I throw out suggestions from other readers. I'm currently working from a rough idea mentioned in the feedback thread.
Although the characters are sort of rebelling at the moment. They're telling me random incoherent pieces of things, which is what's taking so long to put it together. Yeah, I know....I'm a crazy person.
Probably not very helpful in any way to other writers, but that's just the way I work.