Proni, the public record office of Northern Ireland.
What's new at proni?
Proni now has an E Catalogue which is available for free online searches.
It contains over a million catalogue entries, An example of what you can find there. I have a personal interest in Dunturk so i typed Dunturk into the catalogue and the search brought up land leases for Dunturk. If you have an interest in Northern Ireland then take a look.