OilCan is a native Universal Binary multithreaded query tool for PostgreSQL. It supports multiple query windows and multiple queries in one window, and includes a basic schema browser. Each query window gets its own connection. All queries run in their own thread, allowing other operations to continue while a long running query is running.
NSFileHandleExt is an Objective-C extension (Cocoa/GNUstep) for the NSFileHandle class (which handles files/sockets). This extension provides support for much easier network programming for protocols like HTTP, IRC, telnet, etc. (everything that sends messages in lines suffixed by \n).