As most documents are in the care of Manx National Heritage who tend to be a little concerned about unauthorised photo-reproduction I suggest you contact them at the ever helpful Manx Museum at enquiries@mnh.gov.im

Apart from post 1877 (for most part) civil registration documents issued by General Registry (and possibly copyright them ?) few Manx family historians encounter (for obvious reasons) the usual sources - all wills in Manx Museum are microfilmed, as are the usual source for parish registers the 1911 Rolls Office transcription. Likewise for entries in Manorial Rolls + other official documents pre 1911. Under Manx law all deeds of property (+ mortgages etc upon it) must be registered at what is now the General Registry (then Rolls Office) - these deeds are the most probable original document to be handled by a family historian (though their information is generally rather specialised) - currently (tho things will change once the all-Island electronic registry is up) they are public documents in that a copy must be provided to any who asks (on payment of copying fee) but I would ask re reproduction rights.