Making digitised content available for searching and harvesting

I have been invited to give a short presentation to the JISC Digitisation Programme on Friday, giving an overview of different ways of exposing content and metadata. I'll be talking to projects which are concerned with Cultural Heritage content which is being surfaced in websites to support eLearning. Formats vary tremendously. This is the complete list:

• 18th century parliamentary papers
• 19th century pamphlets online
• A digital library of core e-resources on Ireland
• Archival sound recordings 2
• British Cartoon Archive digitisation project
• British Governance in the 20th century: Cabinet papers, 1914-1975
• British Library 19th century newspapers
• British Library archival sound recordings project
• British newspapers 1620-1900
• Electronic ephemera: Digitised selections from the John Johnson collection
• First World War poetry digital archive
• Independent Radio News Archive digitisation
• InView: Moving images in the public sphere
• Medical journal backfiles
• Modern Welsh journals online
• NewsFilm online
• Online historical population reports
• Portsmouth University: Historic boundaries of Britain
• Pre-Raphaelite resource site
• Scott Polar Research Institute: Freeze Frame – Historic polar images
• The East London theatre archive
• UK theses digitisation project

Aside from the obvious stuff like OAI-PMH, Google, RSS, what should I be talking about? Persistent identifiers? Cool URLs? Any other suggestions?