Curia website - http://curia.europa.eu/index.htm - this has transcripts of decisions from 1997 onwards. There is a search form and you can search by date, parties and key words. For cases between 1953 and 1997 you can only search by case number. The numerical lists of cases for the ECJ and CFI are useful as they indicate whether the case is still pending or if it has been removed from the register of cases
 

EUR-Lex - http://eur-lex.europa.eu/en/index.htm - this has ECJ cases from 1954 onwards. You can search by case number, subject or by date. To do this use the Simple Search option

Justis EU - in the Celex section there are ECJ cases from 1954 onwards; summaries of opinions from 1965 onwards and full text opinions from 1987 onwards. You can search for cases by case number, parties and subject. Coverage includes judgments and opinions
 

Lawtel EU - this offers coverage of all ECJ cases (except staff cases) from 1954 onwards. For cases prior to 1989 the information available may be more limited. Cases can be searched by case number, parties and subject. Coverage includes judgments and opinions
 

Lexis Library - includes ECJ cases from 1954 onwards and the All England Reports European Cases from 1995 onwards. You can search for cases by case number, parties and subject. Coverage includes judgments and opinions
 

Westlaw UK - ECJ cases from 1954 onwards and CMLR from 1962 onwards. You can search for cases by case number, parties and subject. Coverage includes judgments and opinions