A NameServer who's only purpose is to take recursive queries from clients and do iterative queries against servers, and to cache the results. Having one of these on your network can improve the latency of connecting to sites around the Internet (as much of the lookup is cached).
If you can, point your CachingNameServer to do a recursive query against your ISP's nameserver, and use their cache too. This doesn't work if your name server is using stub zones. (which you need to use for the MetaNet)