I just wanted to alert members to the Dialog Helper that's included with PowerDesk Pro (now from Vcom/Avanquest; formerly OnTrack; formerly Mijenix). To be honest, I don't normally use it, but I consider PowerDesk Pro (a Windows Explorer replacement) ABSOLUTELY indispensable and therefore consider Dialog Helper free. Also, a version of PowerDesk is included with Vcom/Avanquest's Fix-It Utilities 6 and SystemSuite, both useful programs (however, I'm not certain Dialog Helper is included with these versions of PowerDesk; check with Vcom).
At any rate, DH adds a few buttons to the title bar. It consists of a Folder Tracker, File Tracker, and File Viewer; one or all can be installed. I believe it doesn't meet many of mouser's criteria, but it does offer an unobtrusive interface, recent files and folders, apps to ignore, and more. It might just meet your needs, and if you can use PowerDesk or one of the other utilities, provide a great value.