If you like supernatural thrillers in the vein of Stephen King (though of course not as good!), why not try Ethereal messenger for free? Sorry, only available for Kindle at the moment...
http://www.amazon.com/Ethereal-Messe.../dp/B004GXAWPK
UK:
http://www.amazon.co.uk/Ethereal-Mes.../dp/B004GXAWPK