FindAPhD.com

FindAPhD.com is a comprehensive guide to current research and PhD studentships.
It provides Research topics from many major universities and institutions throughout Europe.
This site also plays host to the Postgrad Forum which provides place for postgraduate students to exchange ideas and pass on advice.

FindAPostDoc.com is another interesting site dedicated solely to postdoctoral jobs worldwide.

See also, FindAProfessionalDoctorate.com, a database of Professional Doctorate Programmes worldwide more appropriate for those pursuing professional rather than academic careers.
A professional doctorate is not the same than a PhD but both lead to the title of “Dr”.