(Possibly the best online dictionary currently) : Xhosa Live Dictionary Best online Xhosa - English dictionary. Translates individual words from/to English or Xhosa.
Xhosa Translator For translating whole sentences. Doesn't work well with individual words.
English/Xhosa/English Dictionary Large database and easy to use search engine. No grammatical explanations, and some entries are inaccurate. Better suited for Xhosa speakers learning English, as many entries contain one English word with long Xhosa descriptions.
Webster's Online Dictionary A list of Xhosa words (and some random phrases) that have been translated from English. Not very extensive. And these resources:
Wikipedia ngesiXhosa The Xhosa version of Wikipedia.
EMbo MaXhosa A blog in Xhosa about Xhosa language and culture.
Multilingual Online Bible The bible in Xhosa (as well as many other languages).
Cape Gateway Has many articles that have been translated into English, Afrikaans, and Xhosa.
iiNkonzo zikaRhulumente Has articles in all eleven of South Africa's official languages.
SA Languages has dictionaries in other SA languages