detecting current <span> tags

Hi all,

Would anyone have an idea how to detect what current <span> style tag is in effect at any given time? More specifically, if i clicked somewhere in the content editor, then performed a 'keydown', is there a way to grab the relevant <span> style tag (if any) that will be applied to the string being entered in the content area? In my case i just need to know how to get the <span> tag to the "left" of the current cursor position.. again, thank you very much for your time!