I found it so interesting to see what information is held about you at the branch office, if you are or were an appointed man.
Name, address, Date of birth, date of baptism, all dates where you have been an elder, ms etc, all the congs you have been appointed in. S2 forms, letters of introduction scanned and available to read
Whether you have been on a JC involving the S77 forms, appeal commitees etc. all the documents, summary letters, etc are all scanned and available in your data file.
If you have given District talks, your ratings (D- to A+) on how good a speaker you are, your ratings, your if you have overseen a department, or been on a District committee etc.
Any letter you have sent into the branch, and any reply all come up in a data search, no matter how old.
In some European countries you can only donate by cheque, these donations are in your file.
If you have applied for Gilead, MTS, Bethel, Construction etc, all the forms even from many years ago are scanned.
You may be 50 years old and have had some judicial trouble in your teens....yep in your data file.
And now with the elder login facility to the society servers, they can check by the cookies what websites you visited before logging in giving them your ID and passwords.
These are the ones I know about, there may be more, however these only apply to those who are or were appointed or brought to the societys attention.