Lexis has a Eur-Lex National Provisions Implementing Directives database. (EURCOM; NATPRV)
Westlaw has the EU-LEG database where directives are followed by information about national implementing measures.
One of the easiest methods for finding implementing legislation is to search the Official Journal of the European Communities at the Eur-Lex website. Once you have found an entry for a particular piece of EU legislation, information about the legislation which various EU countries have passed implementing it will appear in the "bibliographic notice" near the end of the record. The bibliographic notice includes an option to display the "national execution measures." An example is below:
Transposition deadline: 01/01/1990
1. The Control of Asbestos at Work Regulations 1987 S.I. n° 2115 of 1987
Legal act: Administrative measures; Official Journal: Her Majesty's Stationery Office (HMSO)
2. The Control of Asbestos at Work Regulations, Legal Notice No. 49 of 1997 Gibraltar Gazette n° 2,976 of 15/05/1997
Legal act: Notice; Official Journal: Gibraltar Gazette, Publication date: 15/05/1997
No link to the implementing legislation is provided, but you could then engage in country research to find the referenced material. A good general guide to finding foreign legislation is the Foreign Law Guide Database.
There is also the Application of Community Law page. Click on “National Authorities” for a map with links to law web portals for member countries. It also contains a link to N-Lex, an experimental database for national laws of EU member nations.