How about a Windows app that lets you answer calls, place calls, and browse the address book, all via bluetooth?
For bonus points, arrange it with all of the core functionality (pair, answer, dial, browse) in a DLL that exposes a simple API for all of the above, so that the EXE would just be simple UI stuff, calling into that DLL to get all of the real work done. Then plugins can be created for other front ends, using just the DLL plus whatever plugin library each front-end requires.
And let me know when/where I can download it. Thanks in advance.