Tom, like you, I really dig Frank Miller's stuff. So we might have some similar interests.
Here's what I'd recommend:
- Sin City - there are a bunch of trades; the 1st one's still the best
- Daredevil Visionaries: Frank Miller - there are 3 volumes; the 2nd volume's the best
- Daredevil: Born Again
- Daredevil: Love and War
- Elektra: Assassin
- Elektra Lives Again
- Wolverine - collects the original miniseries
- Black Panther: The Client - dark, gritty, and EXTREMELY funny
- Black Panther: Enemy of the State - the sequel
- Watchmen - personally, I think it's overrated, but if you haven't read it yet ... well, you probably should
- Batman: Tales of the Demon - excellent collection of classic Batman stories
- Batman: Son of the Demon - a sequel of sorts
- Green Arrow: The Longbow Hunters
Well, there ya' go. With what you've read so far, I think you'd get a kick out of these.
Have fun, amigo.