Rediscovered one of my software projects from the space-year 2011: Is Locked
It's a little program that allows you to drag and drop files into it and it'll tell you if those files are currently locked (either by another program or Windows itself). I made this for myself as I wanted to quickly know which of the multitude of files I was transferring via FTP were complete.
Any unlocked files can be copied or moved to the clipboard (via a true FileDrop drag operation; not just a textual representation of their filenames) ready to be pasted into an Explorer or whatever window.
Needs a little bit more polishing and then I'll kick it out there; I managed to resist redoing the GUI to be a more modern flat-style, otherwise it may not get released again.
There's so many projects that are on the verge of completion but I just haven't bothered sorting out that last couple of percent.