http://www.eife-l.org/ Eifel site, European Institute for E-Learning professional European independent association that develops research in the area of digital portfolios.
http://electronicportfolios.org/ Helen Barrett's site - the digital portfolios expert offers an uncountable number of resources in English.
http://www.digifolioseminar.org/ Site of the project Digifolio - Digital Portfolio as a strategy for teachers’ professional development.