Tony Russell-Rose has been doing a series of posts on faceted searches.
Since topic maps capture information that can be presented as facets, I thought it would be helpful to gather up the links to Tony’s posts for your review.
Interaction Models for Faceted Search
Where am I? Techniques for wayfinding and navigation in faceted search
Designing Faceted Search: Getting the basics right (part 1)
Designing Faceted Search: Getting the basics right (part 2)
Designing Faceted Search: Getting the basics right (part 3)
And a couple of related goodies:
A Taxonomy of Search Strategies and their Design Implications
From Search to Discovery: Information Search Strategies and Design Solutions
Word of warning: You can easily lose hours if not days chasing down design insights that remain just out of reach. Have fun!