Here are the main features of Strigi:

* very fast crawling
* very small memory footprint
* no hammering of the system
* pluggable backend, currently clucene and hyperestraier,
sqlite3 and xapian are in the works
* communication between daemon and search program over an
abstract interface, this is currently a simple socket
but implementation of dbus is a possibility. There's a
small perl program in the code as an example of how to
query. This is so easy that any KDE app could implement this.
* simple interface for implementing plugins for extracting
information. we'll try to reuse the kat plugins, although
native plugins will have a large speed advantage
* calculation of sha1 for every file crawled (allows fast finding
of duplicates)