I fucking love this series. Has like 8 volumes and now an anime adaptation which is the first two volumes (Phantom Blood & Battle Tendency).
If you're a fan of fighting, "spirit" combat, badass old men, zombies, vampires, glamorous posing and even more badass Nazi loyalists, watch/read this. If you're not, check it out anyway. It gets good, fast.
Anime wise...the first part has that "old" feel, as its adapted from a fairly old manga. It was originally inspired by Fist of the North Star, and you can see the resemblance in it.
Besides that, Lament of the Lamb once I get back around to it. Downloaded it after only having read two or three volumes years ago. Was good then, hoping its still enjoyable now.