Fold3, available 24/7 on the library's website, has added 1/2 million new records from the UK's military.
Details on what's included are here. This is a link to Fold3.
If any of your English ancestors found themselves on the wrong side of the law, you might be able to find records of their misdeeds at oldbaileyonline.org. The Old Bailey is London's Central Criminal Court, and the Proceedings were published from 1673-1913. They contain records of more than 197, 000 trials held there. There are videos and tutorials to help you navigate through the search process.
This index of over 3 million names became available in June at Ancestry. Many census records were lost during the Irish Civil war in the early 1920's, and these land transfer records can help genealogists make family connections back to the 19th century.
Ancestry is acessible at the library only, under "Research Tools" on the library website.
The Queens Public Library and the Office of Court Administration have collaborated to make 400,000 or so naturalization records available online. They include records signed between 1794 and 1952 in the Queens and the Bronx. You can read the article in the Queens Eagle. The database is nynaturalizations.com
Your German ancestors may have immigrated in the 19th century due to changes in climate in Europe .