WWW Virtual Library
This was one of the first international subject arranged gateways and is now quite massive. While it will concentrate on US sites, it does list many UK and European ones too.

The British gateway to engineering resources on the Internet, especially UK-based ones.

ESRC: Economics and Social Research Council
A key source of information on the ESRC's (Economics & Social Research Council) research awards and products, such as books, journal articles, broadcasts and software.