For Weaker Sides, a lot of my inspiration comes from music. I'm a visual artist, but I need music to work and lose myself in the mood of the story. My inspiration playlist can be found at http://www.weakersides.com/connect/
Music like The Birthday Massacre (happy / melancholy goth rock, I guess), Oneiroid Psychosis (dark wave), White Lies, the list goes on.
Also, and I can heartily recommend this to any artist (probably those working on dark / dreadful stuff): dark ambient like Atrium Carceri, Desiderii Marginis, Lustmord --- wonderful, evocative soundscapes galore.
My own gender questions / life issues, social frustrations and love for night and nature also inspire me all the time. And most of my characters are inspired both by my own feelings as well as the lives and peculiarities of my friends - especially my main characters Kyoko and Ashley. I don't always tell my friends, though 
Visually, there's so many artists I admire and get inspired by! I love Edwin Ushiro, Martin Wittfooth, Hamletmachine, Lois van Baarle, Sam Wolfe Connelly, Sam Weber - the list is pretty long.
Interesting topic - great to see how diverse a maker's sources of inspiration can be!