Clojure's a decent choice for writing a cross-platform UI application, using Swing. Java+Swing sucks, but Clojure+Swing works pretty well. I wrote a dependency graph library, dgraph, which significantly reduces the amount of boilerplate required to keep UI state in sync.
I also wrote an embedded database library for Clojure, based on Berkeley DB.
http://github.com/gcv/cupboard
Which specific features make Clojure a good choice? Interactive development and macros.