I have begun doing a lot of javascript development recently, mostly front-end but also using node.js. As I am currently in the transition from large company to startup, they expect me as a front end developer to know how to produce semi decent designs (Which I cannot)

I am looking for a book (or set of screencasts) to give me some good well rounded advice on design. I know CSS, but my design are always awful looking, I also know nothing about Photoshop (and am on Linux and have no access to it)

What are your picks? I am not looking to be a full time designer I would just like to be able to contribute.