Much research requires efficient data searches. For textual analyses that means inter alia knowledge of the lexical universe of the language, in which your data come. For the quantification of several methods, such as frame analysis, it is also important to get an idea about collocations of lexemes.
Word maps are the most useful lexical helpers for social research with texts. They not only list the synonyms and antonyms of words, but also increasingly report collocations of terms as well as word frequencies in general (or topic-specific) discourse.
Wordnet Well-established freeware that maps English with a focus on its North American variety.
Wortschatz at the University of Leipzig Probably the most extensive of word mapping currently available, Wortschatz focuses on German, but has massive collections on English, French, and Dutch. Smaller corpora in Icelandic, Estonian, and Sorabian.
Wörtbuch-Netz A number of historical dictionaries for different German dialects. Includes the Brothers-Grimm-Wörterbuch, probably the most extensive German dictionary of the XIX century. Further readings
Multi and Bi-directional Dictionaries
If you are doing comparative research, these dictionaries might come handy.
Eurodicautom Multilingual Dictionary developed by the EU for 16 languages from the 2003 European Union member states.
Lexilogos Excellent collection of online dictionaries, easily intelligble French interface.
LOGOS Multilingual dictionary, gradually compiled by a network of professional translators.