---Before the 19th Century
Massive violent attacks against Jews date back at least to the Crusades, as well as the York Castle massacre of 1190.
In 1348, because of the hysteria surrounding the Black Plague, Jews were massacred in Chillon, Basle, Stuttgart, Ulm, Speyer, Dresden, Strasbourg, and Mainz -- 12,000 in Mainz alone. A large number of the surviving Jews fled to Poland, which was very welcoming to Jews at the time.[1]
Jews were also massacred during the Khmelnytsky Uprising of Ukrainian Cossacks in 1648-1654.
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In the Russian Empire
The term pogrom as a reference to large-scale, targeted, and repeated anti-Jewish rioting only saw use beginning in the 19th century. The first pogrom of this sort is often considered to be the 1821 anti-Jewish riots in Odessa (modern Ukraine) after the death of the Greek Orthodox patriarch in Constantinople, in which 14 Jews were killed.[2] Other sources, such as the Jewish Encyclopedia say the first pogrom was the 1859 riots in Odessa. The term became common after a large-scale wave of anti-Jewish riots swept southern Imperial Russia in 1881-1884, after Jews were wrongly blamed for the assassination of Tsar Alexander II.
The victims, mostly Jewish children, of a 1905 pogrom in Yekaterinoslav (today's Dnipropetrovsk).
In the 1880s outbreak, thousands of Jewish homes were destroyed, many families reduced to extremes of poverty; women were sexually assaulted, and large numbers of men, women, and children injured in 166 towns in the southwest provinces of the Empire (modern Ukraine). The new Tsar Alexander III blamed the Jews for the riots and issued a series of harsh restrictions on Jews. The series of pogroms continued for more than three years with at least tacit inactivity of the authorities.
An even bloodier wave of pogroms broke out in 1903-1906, leaving an estimated 2,000 Jews dead, and many more wounded. The New York Times described the First Kishinev pogrom of Easter, 1903:
"The anti-Jewish riots in Kishinev, Bessarabia (modern Moldova), are worse than the censor will permit to publish. There was a well laid-out plan for the general massacre of Jews on the day following the Orthodox Easter. The mob was led by priests, and the general cry, "Kill the Jews," was taken up all over the city. The Jews were taken wholly unaware and were slaughtered like sheep. The dead number 120 [Note: the actual number of dead was 47-48[3]] and the injured about 500. The scenes of horror attending this massacre are beyond description. Babes [sic] were literally torn to pieces by the frenzied and bloodthirsty mob. The local police made no attempt to check the reign of terror. At sunset the streets were piled with corpses and wounded. Those who could make their escape fled in terror, and the city is now practically deserted of Jews." [4]---
http://en.wikipedia.org/wiki/Pogrom#Before_the_19th_Century
I didn't mean to imply that only Christians have persecuted Jews during the past 2000 years, but the title of the article was "Christains are Jews' best friends".
claudiustg has done a pretty good job of documenting some instances of Jewish persecution throughout history.
As for the Nazis, maybe they wouldn't have been as "successful" in their slaughter of the Jews had our Christian grandparents and great grandparents petitioned the U.S. and Canadian Gov't not to turn back shiploads of Jewish refugees from Nazi Europe - sending them directly back to the death camps.
Being friends when times are good and it doesn't cost you anything is less important than what happens if things were to go south..
E.G. The Great Depression saw a massive increase in anti-semitism in the U.S. - but that could never happen again, eh?