I tried it out last night, and the interface seems really rich and powerful. It's NINES, a new digital scholarship tool that puts together SW and collaborative tagging in an application targeted and USABLE by anyone, I believe. Worth trying out..

N I N E S stands for a Networked Infrastructure for Nineteenth-century Electronic Scholarship, a scholarly organization in British and American nineteenth-century studies supported by a software development group assembling a suite of critical and editorial tools for digital scholarship.

In NINES you can:

• search and browse more than 60,000 texts and images
• collect documents, articles, images, and ephemera into sets you make
• label your collections with tags you generate
• create syllabi, annotated bibliographies, illustrated essays, and timelines
• explore related collections and exhibits by fellow scholars

Nines it's just a first showcase for Collex, a SW suite of tools targeted at a humanities scholarly practitioners:

Collex is a set of tools designed to aid students and scholars working in networked archives and federated repositories of humanities materials: a sophisticated COLLections and EXhibits mechanism for the semantic web.

Collex allows users to collect, annotate, and tag online objects and to repurpose them in illustrated, interlinked essays or exhibits. It functions within any modern web browser without recourse to plugins or downloads and is fully networked as a server-side application. By saving information about user activity (the construction of annotated collections and exhibits) as “remixable” metadata, the Collex system writes current practice into the scholarly record and permits knowledge discovery based not only on the characteristics or “facets” of digital objects, but also on the contexts in which they are placed by a community of scholars.

It is produced by the SpecLab at UVA, which has done many other interesting projects in humanities and computing.

The Speculative Computing Laboratory (SpecLab) was organized to promote experimental and exploratory research in Digital Humanities. SpecLab projects build on work in applied digital humanities -- at IATH, VCDH, E-Text and elsewhere -- that has established the University of Virginia as a leader in humanities computing. By definition, SpecLab projects are interdisciplinary and innovative, often undertaken with uncertain outcomes for the sake of expanding the methods and assumptions of Digital Humanities.

A couple of screenshots from Nines :

1) you can search items also on the sidebar, and collect and tag them to build your personalized set.

2) the search interface is amazing i think: add/remove constraints from the repositories you want to search in a very visual manner!