• http://nines.org/tools/collex.html

Most literary scholars know about the fabulous online editions of Blake, Rossetti, and Whitman, but in my experience many people who use these editions regularly don't yet know about Collex, "an open-source collections- and exhibits-builder designed to aid humanities scholars working in digital collections or within federated research environments like NINES." NINES is an acronym for Networked Infrastructure for Nineteenth-century Electronic Scholarship; it links together many important 19thC digital editions.

Collex allows full-text searching across virtually all of these editions, and can perform certain basic searches across all editions. Beyond this, it allows you to "collect" the results of these searches, and also to mark them up with notes and tags. The tags are powerful, because you can then see how other readers have tagged your objects. Collex  also offers suggestions: "More Like This . . . "; at present, these are based on details like date and or title, but subsequent versions will include user-generated content.

Saved searches are accessible through a permalink, so that you can incorporate them easily into other formats and share them with colleagues or students. It also allows registered users to subscribe to keywords as Atom feeds--a handy way of extending one's knowledge of an archive.

Some further links: The project's technical description and blog, plus external reviews by Transliteracies and l'Observatoire Critique.