Ive found the ellis island site here quite useful
for finding several relatives, one was my wifes great grandfather who came over from Holland in 1905 (my wifes aunt who was a genealogy buff had been looking for records of his arrival for years - was impressed that I managed to find it in a matter of minutes)
I did find you have to play with spelling and try approximations or various European spellings, as well there are probably more than a few transcription errors.
We had a great aunt josephine who came over to Chicago in the early 1900s and later amassed quite a fortune from being a midwife, chiropractor as well as doing illegal abortions which landed her in jail more than once. When my dad researched his genealogy he found that his great-great grandmother was a state licensed midwife in Bohemia and had a copy of the birth records from her home town and
where she had been midwife to a great many people (another midwife was named appropriately Anna Stork)
when searching for Josephine we knew her name was Petru but found her under Petrova.. 1908 The mystery was that Petru was her married name and yet it was listed in the ships manifest that she was coming to meet her brother Frank Petru in Chicago and that her family in Bohemia was also called Petru. We know that it must have been her as it gave the exact name of her mother Antonia, and that she came from Radenin - which is quite a small town. And yet her marital status was single.
(We know that she was married and know her husbands name but when another aunt was sent to live with her in 1913 and ended up stuck because of the war, by this time there was no husband-) There was some talk that he was an alcoholic so he may have died by then. However back in Europe, they did talk about him being an American businessman.
Delving into the past can be quite interesting, for instance we found that our family name was taken on when our ancestors bought a farm and gradually came to be known by the same last name as the original owners, who had sold it in 1660. The family later sold or lost the farm in the 1870s, and when my father happened to visit the farmhouse in the mid90s and spoke at length with the landlady, who said oh everyone calls me that because I live in the house but my name is actually something else.. (so the farm still continues to name people)
The other items I eventually hope to find is whether a g-g-g-g grandfather who was a retired soldier when he married at 1820 (after 15 years service) actually fought in Austerlitz..
(back in the 60s
Another branch of the family ostensibly came to America after the eldest son fell in love with the (low status) daughter of the local town executioner against the families wishes and the family sold the farm and gave them money to go to America.