I've been thinking for a while about a kind of role playing game that I'd like to play in. It has certain thematic elements and mechanics, with wide open opportunities for story and play. What I really wanted was something with a modern feel, but included fantasy elements. My world should easily allow stories to take place in a modern setting, but also a fantasy one, and support both magic and technology.
Of course, a game like this that immediately comes to mind for me is Shadowrun. Shadowrun has always struck me as the most interesting blend of the cyberpunk future and the arcane in a mainstream RPG. As much as I like the world of Shadowrun, I think it has a handful of limitations that I would not want for my own world. For one, the players are strongly encouraged to be shadowrunners. This means that most stories are going to fall in the domain of "a group of players working together to achieve some kind of anti/corporate goal, who get into trouble along the way". That's fine, but it leaves a lot on the table. Again, you could play something else, but the source material isn't really helpful for this.