The Hellsing OVA series has one soundtrack disc so far. It's called Black Dog, and is available from CDJapan.

Curious? ♫ Listen to some music samples here! ♫ (Link goes to CDJapan's Japanese-language site; please allow popup windows in your browser.)

Tracklist: (1)Song of Demeter  (2)Target Insight  (3)Stand up, Count!  (4)March of a Black Dog and Centipedes  (5)Thousand Fangs, Ten Thousand Eyes  (6)E.M.I.A  (7)Dog's Scratch  (8)Stench of Death and Splashing Blood  (9)Badrick  (10)Dog Shit  (11)Shotgun Circus  (12)Hell's Boundaries  (13)One Million Bullets  (14)Cromwell  (15)Die Fledermaus  (16)Shinobiashi Sashuriashi  (16)Gradus Vita