I find quite a lot of them from both the original timeline and LoS gets stuck in my head, from Bloody Tears (especially the gothic version so often wrongly attributed to being done by Cradle of Filth: [url]http://www.youtube.com/watch?v=vQPF-wgBGis[\url]), various tracks from Lament of Innocence, Treizire de Spirit and De-a Lungul Vietii from Pachislot III, Dying for a Drop of Blood, The Toy Maker, the original cinematic trailer theme for LoS2, Titanic Struggle...
Then again, Castlevania music makes up a pretty hefty part of my platlist of chillout music, and the LoS 2 and MoF osts live in my car (which is called 'Dracul'). Earworming their way into my head has a high possibility.