Yiddish proverb: Most people are more comfortable with old problems than with new solutions.
Whether you are a gentile wanting to learn more about the Yiddish language, or are Yiddish and wanting to learn English to correspond better with the rest of the world, there are plenty of online dictionaries to help you out.
While there are some universities that offer Yiddish programs, the chance of using the language is becoming less and less possible, making it more difficult for students to pick it up.
Harkavy's Yiddish-English, English-Yiddish Dictionary differs from the others in that it's geared more towards Yiddish speakers looking up English, rather than the other way around.
Today Yiddish is still written and spoken in Orthodox Jewish communities, although it is still the first language learned in many Hasidic communities.