The idea of a distributed catalogue of Internet resources integrated with standard Z39.50 library system OPAC interfaces (and hence with retrieval of information on hard copy resources) is already practical at a basic level. Geac's Z39.50 GUI OPAC client. GeoPac, can search remote Z39.50 OPACs, retrieve USMARC records with URLs in 856$u, respond by loading a viewer like Mosaic or Netscape, and utilise it to retrieve and display the remotely held electronic resources on the local workstation. A range of Z39.50 OPACs can be searched server by server, making a basic-level distributed catalogue of Internet resources feasible. At least one other Z39.50 client, Dynix Horizon is close to having similar capabilities. Significant further development and investigation is nevertheless required. A proposed demonstrator project - based around Scottish University Libraries and the BUBL Subject Tree initiative, but sufficiently 'open' to encompass other sites and approaches - is both feasible and essential, and would provide a focus for Z39.50 developments in the UK. Z39.50 clients and associated Z39.50 OPACs describing resources could become preferred network navigation tools with other specific NIDR client types (WWW, gopher, WAIS, others) loaded as required. Library involvement is essential to sustainable Internet cataloguing initiatives.