Recently, we published a simple project called OKAPI Browser.
It is open-source, written in C#.NET and WPF platform. You can fork it, play with it, submit you patches, or you can simply run the Installer for Windows.
Being made crude and fast, it is not as stable as we'd like, but it still might be a handy tool for some of you (i.e. when you want to test a method which requires OAuth).
Also, there were some minor changes made to OKAPI last month (r518):