Tr13 is a library for constructing and using read-only compact (memory-efficient) in-memory trie data structures.
Main benefits for using such tries is both relatively low memory usage (typically 20 - 35% less than raw input size) and low GC impact.
Mailing list: http://groups.google.com/group/ning-tr13-users
(need to write sample code here!)
Check out [https://github.com/ning/tr13/wiki]