Coming from a theme perspective, I think it would be nice to have an option in wp_enqueue/wp_register_style to allow for the specified style-sheet to be loaded last. I realize that the functions already have the "dep" parameter to allow for an array of dependencies, but this is obviously not a solution to my request as one would have to load in each registered sheet they wanted to override, including new ones as plugins are added. This problem has recently come to my attention as the need to add !important declarations in many of my rules has become an issue, specifically in the case of overriding plugin styles (like Gravity Forms).
This request could possibly be answered by answering this: In what order are styles queued, apart from the "dep" parameter? Do they have any semblance of a priority?